The son had not missed a Father's Day in as long as he could remember and, despite all that had happened, he was not going to start now, no matter how forlorn he felt, no matter how discouraged. Through the canopy of catalpa trees, a bright sun cast mottled shadows on the marble and granite monuments. The stillness of the late June afternoon sat heavy as a tomb on the flower-strewn grounds.

Eight months earlier, in October 2006, Jon Cornbleet had come to this same spot, numb, bewildered, and heartbroken. He had listened to the tributes to his father, Dr. David Cornbleet, clung to his mother and sister, and wept as he watched the casket disappear into the chilled black earth. After the ceremony he lagged behind the other mourners, waiting until he was alone. Then, standing in his dark suit, he spoke to the man he called his best friend. "I love you, Dad," he said. "And I will not rest until I find the person who did this."

He clung to those words, found strength in them, all through a long winter of false leads, of staring at videotape until his eyes burned, of hanging information-seeking fliers in the cold until his hands were chapped and red.

But for all his efforts, he had failed. The killer was still out there, out of reach.

Now, in late June, filled with self-disgust, the son looked down at the grave. Bending slightly, he dropped the flowers he had brought. Then, after a pause, he turned to leave. He would not be back, he told himself. Not until he had him. Not until he, the son, had found his father some justice.

* * *

Far away, a different father, a different son. In their story, the father is the bereaved.

His son isn't dead—not in the way David Cornbleet is. But in many ways, Dr. Thomas Peterson feels his boy is just as lost to him, buried not in a grassy field of monuments and stone, but in a catacomb of jail cells on a French Caribbean island, where he awaits charges of murder.

In much the same way that Jon Cornbleet had visited his father's grave, Peterson had hoped to visit his son, 29-year-old Hans Peterson. As of press time he still had not, but was planning a trip to see him in mid-November.

The father now sits across from me in the lobby of a modest hotel in Portland, Oregon, sipping coffee and explaining why he feels as determined as Jon Cornbleet to find justice for a family member he has loved and lost.

* * *

Photograph: Courtesy of Jonathan Cornbleet

Surveillance footage from around the time of the murder showed a man police later identified as Hans Peterson hiding his face behind a bloody garment as he left the building.

This is a story of fathers and sons, grief and blame, obsession and determination, sickness and murder—and, above all, of differing perceptions of justice.

To the public, the murder a little over a year ago of David Cornbleet, a Michigan Avenue dermatologist with an old-fashioned practice, began as an unnerving mystery, one of those disturbingly brutal crimes charged with tantalizing clues and lurid intrigue.

Who would kill the kindly doctor who seemingly had no enemies? Why would the killer carry out the crime in such a viciously personal way—by stabbing him over and over and beating him so badly that, in the words of Jon Cornbleet, "my own family was not allowed to see him in his casket when we buried him"? Who was the mysterious young man caught on the building's security cameras shortly before and after the murder?

The mystery apparently was solved in August when Hans Peterson turned himself in on the French Caribbean island of St. Martin and reportedly confessed. Suddenly, the narrative changed from a murder mystery to a tale of good versus evil. "The Look of Hate," the Chicago Sun-Times declared in bold black lettering above a full-page mug shot of Hans Peterson. And, indeed, with his flat stare, shaved head, and chin shrouded in dark stubble, the accused man exuded menace.

Despite the reported confession, he was fighting extradition. His mother, it turned out, was French, which entitled him to declare himself a national. France declared its sovereignty in the matter, and a French judge ruled that a 1927 national law prohibited Peterson's return to Illinois.

That, in turn, touched off a campaign by the Cornbleet family—led by the son—to pressure France into relinquishing the man who the Cornbleets say is a lifelong U.S. citizen with few ties to France. Among those supporting the effort are Mayor Daley and both U.S. senators from Illinois—Barack Obama and Dick Durbin. The U.S. State Department has weighed in on the side of extradition.

But as tenacious as Jon Cornbleet has been in pursuing justice for his father, Tom Peterson has emerged as equally dogged in arguing that his son—and the entire Peterson family—are also victims. The father claims that the controversial acne medicine Accutane, prescribed to his son more than five years ago by the murdered doctor, turned Hans Peterson psychotic, a condition that possibly made the young man violent enough to kill.

In blog comments he first posted in 2002, Hans Peterson claimed the drug gave him severe headaches and bowel problems, caused his hair to fall out, and destroyed both his libido and his ability to enjoy sexual pleasure. In short, he wrote, the drug had ruined his life—an outcome that he blamed on the "unethical" dermatologist who had prescribed it.

Cornbleet's children say that blaming the drug for the murder is preposterous and an insult to their father. "This whole Accutane thing is a front," says Jonathan Cornbleet. "Hans Peterson—the only patient in my father's 28-year history who thought Accutane did him in—is a coward who is trying to blame a drug for a terrible crime." The son says his father saw Peterson only once, and Peterson took only two doses before stopping the medication. How, the Cornbleets ask, could such a small amount, taken four years earlier, make someone crazy enough to kill—and not just kill, but devise and execute a highly complex plan with the clear aim of getting away with it?

Even Hans Peterson's father acknowledges that it sounds "hard to swallow"—until, he adds, you look more closely at the long and checkered history of Accutane. The drug has been associated with birth defects and numerous physical problems, as well as with psychiatric disorders, including psychosis and aggressive or violent behavior.

Tom Peterson has publicly expressed his condolences to the Cornbleets. But he also has been highly critical of the dermatologist, calling him "one of the villains" as well as "one of the victims." He asserts that Dr. Cornbleet inappropriately prescribed Accutane to Hans, given that the young man had only a mild case of acne. Tom Peterson bases the claim on—among other things—the drug's package insert warning, which states: "Accutane should be reserved for patients with severe nodular acne who are unresponsive to conventional therapy, including systemic antibiotics." The father also says the dermatologist failed to ask Hans about his psychiatric history, which included bouts of depression. Though no consent form is required, such screening is recommended in the package warning. Finally, Tom Peterson claims that the dermatologist gave Hans improper instructions on how to take the medication, which led Hans to take damagingly powerful dosages.

Dr. Charles Zugerman, an associate professor of clinical dermatology at Northwestern University's Feinberg School of Medicine, says he doubts the link between psychiatric disorders and Accutane. Still, he screens his patients for depression and has them sign a consent form outlining potential side effects, such as depression, irritability, and suicidal thoughts. If a patient has a history of mental health issues, he requires that the patient bring a letter from a psychiatrist saying it's OK to prescribe Accutane. Zugerman also says he prescribes Accutane as a "last line of defense" and only for the most serious cases of acne. "It's not for mild acne," he says. "I've never used it as a first-line drug, nor should it be."

What went on during that first visit between Hans Peterson and Dr. Cornbleet may never be known. The only account extant is Peterson's. The Cornbleet family say their father was diligent, responsible, and cautious. They point out that he had never been sued, nor had he faced any sort of professional discipline. "My father was a great doctor and a great man," says Jon Cornbleet.

Hans's father doesn't disagree. But he does believe that the drug caused a drastic and devastating change in his son: "Before, he was somebody you could sit down with, look in the eye and communicate with," Tom Peterson says. "Afterwards, that was gone, and it's remained gone and I believe it will be gone forever."

* * *

Photograph: Courtesy of Jonathan Cornbleet

Happier times: David and Jon Cornbleet pose with puppies, a gift from father to son.

By all accounts, the small 12th-floor complex of examination rooms where Dr. David Cornbleet practiced for nearly three decades bore the look and feel of an old country doctor's office, a throwback to the days when patient records were scribbled on index cards and folders spilled from metal filing cabinets—a place redolent of camphor and rubbing alcohol. The floors were carpeted, the blinds metal. There was no computer.

As for the man who ran the practice, if you were casting the part of the kindly neighborhood doc, you could scarcely have done better than Cornbleet, who was 64 when he died. With his wire-rimmed glasses, silver-daubed hair, and friendly, thoughtful eyes, he knew most of his patients by their first names, and if he didn't, he would by their next visit. Other dermatologists booked their appointments weeks in advance. Dr. Cornbleet always seemed able to squeeze in last-minute visits, particularly if the patient came to him with an emergency—a bride, say, with a wedding day blemish. He did so, his son says, by staying after hours, sometimes until 7 or 8 p.m. His rates were flexible, his payment terms generous. His father, Theodore Cornbleet, had been a dermatologist—had served, in fact, as head of dermatology at Cook County Hospital. The very office in which David Cornbleet practiced, in the 30 North Michigan Avenue building, had been passed along to him by the elder Cornbleet, as had the initialed blue lab coat David wore to all of his appointments.

David Cornbleet's children, Jonathan and Jocelyn, also had ties to the office, helping out during school breaks when they were young, and later, after they were grown, going in on weekends to do their father's paperwork. "Dad and I used to have father-daughter days," recalls Jocelyn, 28, a Loop lawyer specializing in environmental and asbestos issues. "We'd go downtown to Marshall Field's, to see the windows if it was Thanksgiving, then stop by the office."

"My sister and I pretty much grew up there," agrees Jon, a 33-year-old insurance salesman. "It was a very, very old-school office. It reminded me of the old-time barbershop. My father would ask patients about their husbands, their wives, their friends; about college, their dreams. It was more like a social hour with him. He spent an exorbitant amount of time with each person, mostly because he looked on them as friends as well as patients."

Apropos of the doctor's old-school approach, he worked by himself, choosing not to replace his long-term secretary when she retired years earlier. Instead, patients called or knocked on the door, an arrangement that made both daughter and son uneasy. "I never liked the fact that he worked alone," the son told me.

* * *

Photograph: Courtesy of Jonathan Cornbleet

Tom Peterson is also a doctor who has a son and a daughter. Raised in a suburb north of Milwaukee, Peterson earned his undergraduate degree at the University of Wisconsin, in Madison. While traveling around Europe the summer before medical school, he met a French woman named Jacqueline Lebas at a youth hostel in Scotland. The two married in 1972. Jackie became a dual citizen in 1991.

Hoping to land a job in emergency room medicine, Peterson began looking for small hospitals that would hire a doctor fresh out of school. He found one in Roseburg, Oregon, and the couple moved there in 1974. He initially chose the ER, he says, "because you had to think fast, come up with diagnoses, and keep your cool through it all. But when you were done for the day, you were done." His outside interests—marathon running and triathlons—would eventually lead to his long-term career path. "I would get injuries, and runners would come to me for help curbside," he says. "Eventually, someone said, 'Why don't you just open an office in sports medicine?'"

He did, and in July 1978, the couple had their first child. Blond, blue-eyed, Hans Peterson was named after his great-grandfather Johann, a homesteader who had come to the United States from Sweden. Four years later, the couple added a daughter. (Peterson asked that she not be named, a request honored by Chicago.)

Both children were shy. The sister participated in gymnastics and ballet, Peterson says, "but was really very withdrawn through school. She just kind of liked observing what was going on and not being a part of it."

There was a history of depression in the family, though early on the son revealed little sadness. A picture of Hans at the age of 15 shows a fair-haired boy in shoulder pads, down on one knee, clutching a football and beaming proudly. "He was a happy child in his early years," the father says. "He was crazy about football, although he was not a real good player. But he loved the game and he loved wearing the uniform—that was just the coolest thing for him."

Russ McIntosh, a longtime friend of the Petersons', recalls that Hans was never a big conversationalist, "but he was always engaged," he says.

When Hans reached his high-school years, however, a sense of melancholy began to show itself. "He started getting more and more shy or being more and more aware of being shy," the father says. "When you get to be teenagers, all the little social structure starts. And since he wasn't the kind of person who easily engaged people in conversation, he kind of felt left out of things. Not that people didn't like him. He was very likable and everyone was fine having him around, but he wasn't in the in crowd. He didn't have much of a social life and he didn't date much" beyond taking McIntosh's daughter to the prom.

One day, Tom Peterson says, he noticed that his son was reading a book on how to overcome shyness. "I asked him what that was about, and he said, 'I just can't seem to light people up or get girls to want to go out with me. I feel lonely.'"

The father says he was concerned enough about the depression to take his son to a therapist. "He'd get into a pretty blue mood where he didn't want to do anything," the father says. "As he got more and more into teenage years, you started seeing it more and more, to the point when he was 16 he got put on antidepressants [Zoloft] for the first time." By then Tom and Jackie Peterson were having their own troubles. They divorced in 1994.

* * *

Every day, as evening gathered, the dermatologist went through the same routine. "My dad was very methodical," recalls his daughter, Jocelyn. "Every day at about six he would call my mom and say, 'I'm finishing up; I have one more patient.' Then he would transfer the phones so that they forwarded to his house" in Lincolnwood, on the Northwest Side.

By 7:30 p.m. on Tuesday, October 24, 2006, however, Dr. Cornbleet's wife, Aileen, had not heard from him. She immediately called Jocelyn, who was walking her dog downtown. "It's nearly 8 o'clock and I haven't heard from your father yet," her mother said. "I'm concerned." Shortly after, Jocelyn received a call from her brother. "You're the only one in the city," Jon said. "Can you go and check on him?"

The daughter felt an immediate sense of dread. Something had to be very wrong. Had he had a stroke? A heart attack?

Walking into her father's office building, a high-rise across from Millennium Park, the daughter approached the security guard. "Have you seen Dr. Cornbleet?" she asked. The guard hadn't. Panic rising, Jocelyn took the elevator to the 12th floor and walked down the marble hall to the door of her father's office.

* * *

 
Photograph: Courtesy of Tom Peterson

His depression waxing and waning, Hans Peterson began attending Southern Oregon University, but after a quarter he transferred to Oregon State University, where he overcame his shyness enough to win acceptance into a fraternity, Theta Chi. The school year passed uneventfully. Hans, however, was restless. "I think he knew how smart he was," his father says, "and he wanted to kind of bump brains with a place that would push him a little bit. He wanted to be a part of the bigger college scene. So he decided to go to [the University of Wisconsin] because my father went there and I went there." After a summer at home in Oregon, Hans transferred and again joined a fraternity.

His grades were up and down, depending on his depressive moods. "He would get a 3.8 one semester and a 2.6 the next," his father says. When he would come home for visits, he would sleep until noon, a fact that concerned his dad. "It was like he did not want to get up and do the day. He didn't really care what he had to eat."

Still, Tom wasn't alarmed. "It seemed odd that he would want to stay in bed until noon on a nice day," he says. "But after a while I just kind of accepted it. The downs were never so bad that I thought he would kill himself or anything. I just kind of said, Well, I guess that's who he is. He's a night owl. I'm a morning person. Should I love him for who he is or should I try to change him?"

Occasional upswings helped allay the father's worries. "There were times when he seemed less depressed," Tom says, "not exactly bubbly. But he would get up early, go jogging."

A cap-and-gown photo from 2000 shows a grinning Hans Peterson displaying his diploma. The picture also reveals acne blemishes around his mouth and on his chin.

With a newly minted economics and philosophy degree, Hans landed a job as a clerk to a stock options trader in Philadelphia. "He really enjoyed it," his father says. "They recognized he was smart and let him try some things on his own." Then came 9/11. "After that, stock options trading tanked and so much for that," he says. Still, after a stint on unemployment, Hans was able to find an options job in Chicago. He lived at 2470 North Clark Street, his father says, and took a bus to work. It was also here, about this time, in the spring of 2002, that he found motivation to confront his recurrent skin problems. "He called one day [in April] to say he was going to visit a dermatologist," recalls Tom Peterson.

Two days later, Hans called again. "'I went to a doctor for the acne and he gave me something called Accutane,'" the father says his son told him. "'Now I have a horrible headache; I feel really depressed; I can't concentrate.'

"'You shouldn't be taking it,'" Peterson says he told his son. "He said, 'Well, I already stopped.'

"So then he starts calling me three or four times a day, telling me how horrible he's feeling," Peterson says. "I told him, 'OK, wrap up your stuff and put it in storage and I'll get you a plane ticket to fly home tomorrow.'"

The father says when he met his son at the airport, "there was just this look of terror in his eyes. He was shaking and distressed and complaining about these roaring noises in his ears. I took him home and he would curl up on the couch holding his head. He didn't want to eat. He couldn't sleep. I would try to play music, and he would say, 'No, that hurts my head.'

"My reaction was shock—Oh, my God. . . . I tried to make him as comfortable as I could. I arranged for him to see doctors: neurologists, psychiatrists, psychologists, ear specialists. And the consensus was, he was psychotic."

The father says his son became deeply withdrawn, rarely venturing out of his room. His symptoms improved enough, however, that after several months he took a trip to Normandy, France, with his mother for a two-month visit with relatives. (Jon Cornbleet has said Hans Peterson has never lived in France and therefore questions his ties to the country. Tom Peterson, however, insists that Hans has been there "at least a dozen times. He's got 15 cousins, six sets of aunts and uncles there.")

* * *

Photograph: Courtesy of Tom Peterson

Since it was first approved by the Food and Drug Administration in 1982, Accutane has been—and continues to be—one of the most highly effective, profitable, and controversial acne drugs available. Originally studied for use as a chemotherapy agent, the medication also showed an extraordinary ability to clear up the most virulent forms of acne—in particular, severe nodular blemishes.

To date, the drug has been prescribed to more than 13 million patients, and it brings its manufacturer, the New Jersey–based Roche Pharmaceuticals, some $700 million in annual sales. From the beginning, however, the drug's potential side effects raised deep concerns. Pregnant women, for example, were warned that the medication could cause birth defects. The drug also was linked to premature birth, miscarriage, and infant mortality.

Roche Pharmaceuticals has also admitted that Accutane can cause depression, psychosis, and, in rare instances, thoughts of suicide. Indeed, a product information insert included with the drug warns patients to stop Accutane if they or a family member notices symptoms of depression or psychosis. Those symptoms include the patient's becoming more "irritable or aggressive" than usual, or "acting on dangerous impulses."

In addition, a 1998 FDA memo states: "Given all the pieces of evidence available, it is difficult to avoid the conclusion that Accutane can adversely affect the adult human brain in clinically significant ways and that Accutane use is associated with severe psychiatric disease in some patients." The memo recommended "active consideration of removal of Accutane from the market."

Accutane remained available, but the FDA ordered Roche to strengthen the warnings on the drug's packaging to alert doctors to the risks of "depression, psychosis and, rarely, suicidal ideation, suicide attempts and suicide." The FDA also sent a letter warning Roche to cease "false and misleading" advertisements that promoted Accutane as an "effective treatment of severe acne . . . [that] minimizes negative psychosocial effects such as depression and poor self-image."

Many of the concerns over the drug have arisen from several high-profile deaths associated with the drug. In 2002, Charles J. Bishop—a 15-year-old high-school freshman who had been prescribed the medication—killed himself by piloting a stolen Cessna 172R into the 28th floor of the Bank of America Plaza in Tampa, Florida. On May 14, 2000, the son of Michigan congressman Bart Stupak shot himself in the head hours after his junior prom. His father blamed psychological side effects from Accutane and launched a campaign against the medication that continues to this day. "This drug represents a public health concern for the American people," he declared in a congressional hearing. "We cannot allow the drug manufacturer and the FDA to continue to turn a blind eye to the lives lost, families devastated, and dreams dashed by an acne drug."

Roche maintains that the drug is safe when used correctly and insists that no study "has found any cause-and-effect relationship between Accutane and psychiatric events." (Roche responded to requests for an interview with a statement reiterating its position.)

Opinions within the medical community continue to vary. "I have myself given it to hundreds of patients and have never seen a significant side effect," says Robin Gehris, a pediatric dermatologist at Children's Hospital in Pittsburgh. "I think to say that a person took a drug and four years later that [a crime] was that drug's fault, I think is just the hugest stretch I've heard."

In a study of Accutane two years ago, J. Douglas Bremner, a psychiatrist at Emory University, found that the drug caused a decrease in brain function in the section of the brain regulating mood and impulse. "My opinion is the risks of depression, suicide, violence, and aggression from Accutane have been downplayed in the past," he says.

Members of the Cornbleet family scoff at the notion that two doses of Accutane taken four years before their father was killed could lead to murder. Such a claim, says Jocelyn Cornbleet, is simply a ruse to "get the focus off of [Hans Peterson] and put it on the big bad pharmaceutical company."

Tom Peterson acknowledges the skepticism. "I have to agree, it's hard to believe," he says. "But there it is."

Whether or not Accutane drove Hans Peterson to violence, as he and his father claim, it's clear Peterson developed an obsession with the drug. On May 12, 2002, using the login name of "hansp," he signed up for a membership with the Accutane/Roaccutane Action Forum Group—a blog for people who believed they had suffered adverse side effects from the drug. Within five years, he had posted more than 60 times to the blog, starting with his first entry on June 16, 2002: "In late April, I went to see a dermatologist for my very mild, but persistent acne. He was an unethical old man who suggested Accutane. I took it for 2 days. Then I got a bad headache and read about the side effects. I stopped right away. I thought that I was safe having only taken a few pills. However, about 5 days later, I got really depressed and couldn't sleep. My ears started to ring. . . . My appetite went away. . . . A couple of days after this, my libido vanished and I lost virtually all sexual sensation. . . . It has been over a month and a half since my very brief experience with Accutane and most of these effects have not improved at all. Am I permanently affected from taking an acne medicine for 2 days?"

Several news outlets have reported that Peterson claimed the drug caused him to be impotent. But a posting by Peterson on November 15, 2002, suggests otherwise. "Since taking a relatively high dose of Accutane for a very short period of time 7 months ago," he wrote, "I have been experiencing persistent sexual problems. I would describe it as a loss of libido and sexual sensation. . . . I can get an erection and otherwise function normally. The pleasurable sensation is just gone."

In 2002, despite his growing obsession—and seemingly out of the blue, his father says—Peterson decided to take the law school admissions test. "He doesn't get the book, doesn't take the class, but scores phenomenally high," Tom Peterson says.

Shortly after, his son accepted a scholarship to Yeshiva University's Benjamin N. Cardozo law school in Manhattan and moved to New York from Oregon, where he had been living with his mother. "So starting in January of '03 he begins classes," the father says. "By the fall of '04, he's two-thirds done and in the spring of '05 he's supposed to graduate." By this point, Hans Peterson lived in an apartment in the East Village with two roommates.

The father says he tried to reach his son there several times as the graduation date approached, but "suddenly, he wasn't returning my phone calls. I finally called and said, 'If I don't hear from you within 24 hours I'm going to call the police and report you as a missing person.' Well, then he calls back and says, 'I quit law school. I stopped going to classes four months ago, and I'm doing Internet gambling.'"

Unbeknownst to his father, Hans had turned inward again, and more profoundly than ever. He had grown "increasingly antisocial, manic, prone to isolationist behavior, staying awake for days," a friend of one of Hans's roommates wrote to Jon Cornbleet in an e-mail. "He would shun large groups and [the roommate] recalls being unintentionally engaged in discussions about Accutane and the effects of the medicine," said the friend, a 25-year-old marine who is now in Iraq. At some point, Hans also began talking to the roommate about harming the prescribing dermatologist for what "he had done to him," the marine added. (Neither the roommate's name nor that of the marine has been released.)

On October 19, 2006—five days before the murder—Hans set out to do just that, police believe. Renting a car in New York, he left the city, bound for Chicago. Police say he had made an appointment, using a fake name, with Dr. David Cornbleet.

* * *

Photograph: Courtesy of Jonathan Cornbleet

On the 12th floor of her father's building, the first thing Jocelyn Cornbleet noticed was that the door to his office was unlocked. Her father always locked the door this late. With an impending sense of doom, she turned the knob and stepped inside.

The office included a reception area and three tiny examination rooms. The middle door was closed but marked by a smear of red. "I knew he was in there," the daughter says.

Peering in, she saw that the room was a mess. "Obviously there had been a struggle," she says. "The blinds were bent and weren't closed properly. The stuff on his desk was all over the place." When she looked down, she saw her father in a pool of blood. One of his shoes was off. He had deep cuts on his hands and feet. Police would later say that the doctor had been bound with duct tape, but the daughter didn't see any. The family would also learn that the killer allegedly had planned to use a blowtorch as part of a torture scheme.

"I didn't cry and I didn't freak out," she told me one afternoon recently. "I immediately called 911," she says. But when an operator came on the line, she couldn't speak. "I was yelling at the person because I couldn't say what I wanted to say—that he was in this room and here was the address. Finally, I just screamed, 'There's been a murder here. You need to send someone!'

"Then I had to call my mom," she says, "which is the most horrible thing you can ever do. I said, 'Dad's dead.'"

The police and the detectives arrived within minutes. They blocked off the room. They introduced themselves, then began asking questions. At first they pressed her about her whereabouts that night. "Do you think I did this?" she asked. As the investigation continued, the questions focused on the doctor. Was he having an affair? No. Could he have been using drugs? No. Was he gay? Did he have a lover? No. No. The daughter says that police also cast a suspicious eye on her mother. Was this about insurance? No.

The family understood why such things needed to be asked. Still, the children say, the mere suggestion that their father was involved in something shady hurt. "When someone gets killed in that way, I think people automatically assume he is having an affair, or doing drugs," Jocelyn says. "My dad was the most clean-cut person there could be. It was very important for us to clear his name."

Investigators soon found a woman who had shared the elevator ride down with the likely killer. The young man, a bloody towel or jacket held to his face, "was shaking and breathing very heavily," Jocelyn says the woman told police. "We thought that he had been punched in the face and maybe his nose was broken, because the woman who rode down with him in the elevator said there was blood all over his face. [In his confession] Hans admitted there was much more of a struggle than he had bargained for." (Police stopped commenting on the case after Hans Peterson's arrest.)

Footage from video surveillance cameras, which would be played repeatedly on news broadcasts, showed a man with a messenger bag walking into the building. Wearing jeans, a red baseball cap, and a waist-length jacket, he pushes the "up" button and then steps into the elevator. Forty-five minutes later, the cameras capture him re-emerging, his face now hidden by a bloody towel or jacket. Police say the man, who hurries down the hall and out a revolving door, is Hans Peterson.

Jocelyn Cornbleet says police told her what happened next: Hans Peterson ducked into the parking garage, climbed into his rental car, and drove back to New York. He stayed there for about two months. Then, around Christmastime, he packed a suitcase and caught a flight to Oregon to see his mother and father.

Tom Peterson says he noticed nothing amiss with his son, beyond the symptoms he had shown since taking Accutane. He did notice that Hans was spending time on the Internet, researching the Caribbean island of St. Martin. On the last day of his visit, the son revealed why: He was moving to St. Martin to resume his career in Internet gambling.

From his new Caribbean home, Hans Peterson reentered the blogosphere. Only this time, he did not seek out an Accutane support group. Instead, he sought information from a site devoted to Asperger's syndrome—a milder variant of autistic disorder. In his second posting (republished on theoutfitcollective.blogspot.com, a Web site run by Chicago crime writers), he wondered whether he might have the syndrome—much as he wondered if Accutane were to blame for his difficulties: "Hi, I have always been different from most of my peers—extremely quiet, unable to engage in any sort of small talk, somewhat obsessive, intelligent, and somewhat unable to make friends. Many of these qualities I attributed to the fact that I grew up in a house in the middle of nowhere, with no immediate neighbors, and the way that may [sic] parents were rather different than most people in the town that I lived near. (White trash town—my father is a doctor, my mother from France, and not used to many American customs.) I was always considered talented and gifted in school, but I struggled socially (many people felt I was mute), and I have never been in a real relationship in my life despite my above average physical attractiveness. I am now 28 years old and recently moved from the United States to an island in the Caribbean."

* * *

Mourners packed the Weinstein Funeral Home in Chicago for the dermatologist's funeral. Adding to the unreal feeling of the event for the family was an instruction by police to keep an eye out for anyone among the mourners who didn't belong—killers sometimes showed up at such ceremonies for their victims, they said. "I gave a speech and the whole time I was looking to see if there was a young man sitting by himself," the daughter says.

Jocelyn's eulogy took the form of an open letter to her father. "Not only did you devote your life to your family," the daughter said, while television cameras whirred and reporters scribbled, "but to the literally thousands and thousands of patients you saw and helped. Each one you treated as if they were the most important person in the world because for that moment, their problem was your dedication and goal to fix."

They buried David Cornbleet, dressed in the blue doctor's coat that had once been his father's, in the New Light Cemetery in Lincolnwood. After the ceremony, Jon Cornbleet stood alone at the site. "Dirt was being piled onto the grave and I was just crying my eyes out," the son recalls. "And I said to [my father] right then and there, no matter what I had to do, I wasn't going to give up. I didn't know thing one about being a detective, but I'm a smart guy; I'm a resourceful guy. I told him, 'You were an awesome father—you were my best friend and I'm going to do this for you.'"

* * *

Photograph: Courtesy of Jonathan Cornbleet

Gathering together a few days after the funeral, the Cornbleet family formulated a strategy. The son would handle the media—the more publicity, the better the chance that someone would step forward. Next, the Cornbleets decided on the best way to reach people who might know the killer, a young man. "We [felt that we] needed to come up with a way to attract someone who's in their 20s or 30s," says Jocelyn. "So we asked ourselves, 'How do they communicate? How do they actually talk to one another?'"

Recalling that another family had used YouTube to solicit tips after an accident, Jocelyn suggested putting the surveillance tape on the video-sharing site. Meanwhile, the daughter's fiancé, Dan Drucker, turned to MySpace. "He said, 'We gotta hit the Internet, because the guy's young; his friends are going to be young.'"

Over the next several months, Jon devoted his life to the case. He spent hours in his home office soliciting MySpace "friends." He updated the Web site Drucker had created with any new development. Trudging downtown in the winter cold, he papered the Loop with fliers.

The plan worked. The Web site attracted thousands of hits. Tips poured in. The case landed on numerous TV programs, everything from The Today Show to Inside Edition. Geraldo Rivera devoted a segment to the investigation. The family passed its information to detectives. Jon offered a $25,000 reward.

After an initial flurry, however, the case seemed to stall. Then, last February, a video surfaced. A young man shopping at the Home Depot on North Halsted Street was captured buying an unusual item that had been found at the murder scene. The object, which detectives have not revealed, had been bought on September 30, 2006, more than three weeks before the murder.

At the family's expense and with the blessing of police, Jon turned to a Virginia research firm used by the FBI to enhance the surveillance tapes from Home Depot and 30 North Michigan. The family's hopes soared. Then police gave them the bad news. The young man in the Home Depot video was not the killer. His alibi was airtight.

"We were extremely disappointed," says Jocelyn. "At first, you get a whole lot of hits, a lot of people who view the Web site and give you information. Then all of a sudden it stops. You find DNA at the scene and look through the database and it doesn't match. You have all these leads that didn't go anywhere."

Winter became spring. No new leads, no promising developments.

* * *

Then, one night, 24 weeks after his father's murder, Jon Cornbleet received a message on MySpace from the marine friend of Hans's former roommate. In it, the 25-year-old marine passed along the concerns expressed to him by the roommate and the name of the person the marine believed had killed David Cornbleet: "Hans Rudolph Peterson." Jon called police and then his sister. "This is the one," he told her. "This is the person. It checks out."

Police began to match evidence from the scene to Hans Peterson. "My dad had a card for [him], one of his patient cards, including the date he came in and the prescription my father wrote," the daughter says. While the family waited, fearful that the suspect would somehow elude arrest, detectives assembled the case. They secured a warrant to search Peterson's former New York apartment. They matched DNA found on a cigarette butt to the DNA found at the murder scene.

Jon Cornbleet returned to his father's burial site on June 17th—Father's Day. The weather was warm and humid. Yes, he now knew who the killer was, but the suspect still walked a free man. Jon wept as he once again addressed his father. "I stared at his grave with disgust for myself," he says. "I had promised him the last time that if he gave me the strength that I would bring him justice. . . . I had to tell him, 'I'm doing everything I can, but it's not enough. I'm not getting the job done.' It was horrible."

Eventually investigators located Peterson through a forwarding address provided to them by the marine. On St. Martin, in early July, Hans learned authorities were closing in. He called his mother, Tom Peterson says. "He said, 'Mom, I need you to come down here.'" Then Hans turned himself in. Jackie Peterson, in turn, called her ex-husband. "Hans is in a French prison," she said, "and he confessed to murdering the dermatologist who gave him the Accutane."

Tom Peterson says he didn't believe it. "I thought, Maybe he imagined he murdered the doctor. Then I did a Google search: Chicago, murder, dermatologist. And I watched the videotape of the guy walking into the building. And I thought, 'That's his walk.'"

* * *

In the months that have followed, the two families have been consumed by different battles. The Cornbleets, led by the son, have relentlessly pursued the extradition of Hans Peterson from Guadeloupe—another French Caribbean territory where Peterson was transferred and where he awaits his fate. Hans's father, on the other hand, has begun to speak out against Accutane and in defense of his son.

To Jon Cornbleet, Hans Peterson is a "coward" afraid to face justice here, someone gaming the system to avoid a harsher sentence than he would receive in France. "He's made an absolute mockery of justice, of France and America's judicial system," the son says.

That hasn't stopped Cornbleet. As in the pursuit of his father's killer, he has been unrelenting in his fight to win extradition. In addition to numerous media appearances, he has organized e-mail and letter campaigns. He has won support for his cause from local, state, and national officials.

One of those officials, Cook County state's attorney Richard Devine, has been particularly vocal. He has argued that France's extradition treaty with the United States allows for discretion and has said that, no matter what, he is determined to continue the fight. (Peterson has not been charged here, nor will he be unless extradition is granted.)

The French, however, remain unmoved. "Our law provides very clearly that French nationals are not to be extradited," Jean-Baptiste de Boissière, the French consul general in Chicago, has said. "It's a law which doesn't give room for maneuvering." Thus, says Anthony D'Amato, a professor of international law at Northwestern University, "it's futile for Mayor Daley to go to France and ask them to send a guy back. No official can do it without violating French law."

As this story went to press, French authorities were waiting to charge Peterson pending the outcome of their investigation. One near certainty: Peterson would face lighter penalties in a French court than in the United States. Even under a life sentence, he could be released after 20 years, Devine says.

Such a possibility is anathema to the Cornbleets. "For us, 20 or 30 years is not sufficient," says Jocelyn. "He would still have another 20 or 30 years of life, as if it [had] never happened."

Tom Peterson, meanwhile, has devoted himself to defending his son and preaching against a drug he believes destroyed not only his son's life, but his own and his family's.

"I think the drug made him psychotic," he says. "And once you're psychotic the door is open to all kinds of things. You can sit there and ruminate about what happened to you and your anger can spill over. Obsessiveness is part of psychosis."

In any trial—be it here or on French soil—Accutane will likely play a key role in Hans Peterson's defense. If the claim is insanity, however, he will face a heavy burden. Under U.S. law, Peterson would have to argue that he could not distinguish between right and wrong—a position made difficult by the lengths he allegedly went to in order to cover up the crime. An insanity defense might be even harder in France, says D'Amato, the Northwestern University law professor. Unlike courts here, the French judicial system uses a three-judge tribunal that chooses its own expert witnesses. That means Hans would be unable to bring his own expert to testify as to his competency.

A trial on French soil would also place a strain on the Cornbleets. They and any other witnesses would have to travel to the chosen location. Chicago police would help French prosecutors by providing evidence. Even if Peterson were convicted and punished by the French, it would not shield him from prosecution in the United States should he ever return, according to Devine.

For his part, Tom Peterson at this writing had yet to consult with a criminal attorney. And anyway, he says, "I am not bringing up the Accutane part of this story to create a legal defense. I am trying to educate the public about what really happened and to expose the corruption of Big Pharma, the FDA, and the majority of doctors."

That doesn't mean he sees no link to the crime from the medication. If not for the Accutane, he says, "[Hans] would have stayed in Chicago. He would have found his way in the stock options world, and despite his shyness, I believe he would have found a life for himself."

* * *

In the late afternoon of an early fall day, Tom Peterson looks weary. Since his son's confession, he says, he has received "horrendously harassing phone calls," people saying things such as "Aren't you proud of how you raised your son?" and "You must be a horrible person yourself."

Still, he feels deep sympathy for the Cornbleets and acknowledges that they are victims of a terrible tragedy. "I can understand his opinions," he says of the other son in this case, Jon Cornbleet, "and I'm not trying to put him down for it. My feeling is, [Hans] is my son. And in spite of whatever happened, I love him and feel that he should have" a chance to defend himself. "I'm speaking as a parent for my child," he adds. "If that wasn't the case, I don't know if I'd be saying it either. But if you're going to ask me my personal opinion about my child, I'm going to tell you, and I don't need to apologize for that."

* * *

The son has not returned to his father's grave and won't anytime soon, most likely. "I have not gone back as of yet because everything is still kind of up in the air," Jon Cornbleet says. "I am not sure if I can face his grave until Hans is brought back to the U.S."

Jon says he has considered reaching out to the other father, Tom Peterson. "Contrary to what he probably thinks, my heart does go out to him," Jon says. "Let's face it: For all practical purposes, his life is ruined. And he's right: His son is never going to get married, never going to live free, never going to spend another Christmas with his family. I do think about that. At the end of the day, what I think is, this is a major tragedy between two families."

Sitting across from me, staring into his coffee, the father shares similar feelings. He has never spoken with Jon Cornbleet. But he would be willing to. Maybe someday.

Meanwhile, in the waning afternoon, the father picks up his briefcase, stuffed with documents and studies on the drug he believes took his son, and heads home, alone.