This story originally aired Dateline NBC on March 16, 2008.
CHICAGO — "He always calls by 6:00 to 6:30 and he hadn't called," said Jon Cornbleet.
By 6:30 p.m. on a cool autumn evening, a Chicago doctor, who ran his life like clockwork, had not called home from his office on Michigan avenue.
"Your body is kind of numb," said the doctor's daughter, Jocelyn Cornbleet. "It's shaking. It's-- just it's on automatic pilot."
His family didn't know it yet, but dermatologist David Cornbleet had come face to face with a time bomb, an unlikely bundle of rage whose fuse had been lit long ago.
JON CORNBLEET: I still have nightmares about it.
ROB STAFFORD, CORRESPONDENT:What has your family been through in the past year?
JON CORNBLEET: Absolute hell.
It began with the stabbing death of a gentleman that was so brutal, it seemed personal. Who would have done it? And why? Desperate to solve the murder of this old-school doctor, his family went high-tech, employing MySpace, in a search that would lead overseas and into frustrating legal territory rarely charted before.
The mystery begins with a man many considered a model citizen. To his son, Jon, and daughter, Jocelyn, Dr. David Cornbleet was both a father and a friend.
JON CORNBLEET: He was an amazing father. In the last few years I considered him more to be like a best friend. We'd talk all the time. And I actually worked for him voluntarily for the last ten years. Every single Saturday I volunteered to help him out just because I enjoyed being around him.
To his patients, his family says, he was an old-fashioned doctor, a sole practitioner who worked alone in his office without nurses and in the last few years, not even a receptionist. He drove a Buick, lived in a modest house, and cared more about medicine than money.
JOCELYN CORNBLEET: He wouldn't charge people. If we had friends who couldn't afford it, he would see them and not charge them because he just wanted to get people well.
And he volunteered to help strangers as well. He treated burn victims in New York after 9/11 and patients in Louisiana after Hurricane Katrina.
JON CORNBLEET: He just loved to give. He loved life, very happy person, happy-go-lucky guy.
But he also very predictable when it came to time. The doctor woke at 4 a.m., walked his dogs, read several papers, showered, dressed, left home at 6:30 p.m., and arrived at the office at seven sharp. His son says he worked straight though the day before calling home between 6 and 6:30 p.m., and then driving back to the house for a home-cooked meal with his wife Aileen. They were married 38 years.
JON CORNBLEET: My dad is the most meticulous person in the world. I mean, he does everything basically at the same time. And I knew at that point there was something wrong with why he didn't call.
So Jon called Jocelyn to check on their dad because she lived closest to his downtown office. She arrived within 20 minutes, her fiance not far behind. She found the door to his 12th floor office unlocked,and quickly walked past his three examining rooms.
JOCELYN CORNBLEET:The first two rooms, the doors were closed. The last one was open, so I went straight back into the last room and there was nothing in there. And I turned around, and as I was turning around, on the door to the second room, which was closed, there was blood across it. So I knew that he was in there and opened the door and saw him on the floor.
He was dead. Her father was dead. She immediately called 911.
JOCELYN CORNBLEET: I said, "I need an ambulance here. My father's been murdered."
Then she phoned her mother.
JOCELYN CORNBLEET: I said, "Dad's dead."She said "Oh my - oh my God!There was a lot of "Oh my Gods."
She also called her fiance, Dan Drucker, who arrived moments before the police and stopped at the first floor security desk.
DAN DRUCKER: I asked the security guard who was sitting there, "What floor is Dr. Cornbleet on?" And she goes, "The 12th floor." And I go, "I think he's just been murdered." And it was the reaction she gave was very kind of shocking. She was like. "Oh, my God - I can't believe it." Not so much like a shock of, like “What are you saying?” But more of like “That explains it,” 'cause it seemed like she knew something from before.
ROB STAFFORD: It seemed like she had seen something?
DAN DRUCKER: Yeah, she had seen something.
Turns out she had seen something - a man acting strange, with blood on him. Luckily, so had the building’s security cameras. Soon, the police would have this tape, which just might tell the whole story: Who was this man? And did he murder a beloved doctor?
Dan Drucker arrived at Dr. Cornbleet's office just minutes after his fiancee had found her father - murdered.
DAN DRUCKER: She was just a complete wreck, crying. [She] points me in the direction where in the office where he is. I just push open the slightly. I see him laying there. That was enough information for me. My main job then was just to console her.
Later, the sad job of identifying Dr. Cornbleet fell to his son, Jon.
JON CORNBLEET: They said that he was so mutilated and so beaten up that they just showed me, actually, a picture of his head. My father, even at 64, had a pretty full head of hair and his hair had been shaved. So it was very hard to look at. I still see that image all the time.
At the funeral, Jon was the last to leave and the first to decide his family would play an active role in the investigation.
JON CORNBLEET: I looked down in his grave and I was crying . And I made a vow to him right then and there. And I said, "I'm not gonna come back until I find justice for you."
The Cornbleets were grieving, but they were determined to find their father's killer, and to do that they would have to learn everything, no matter how difficult, about what happened before, during and after the murder.
ROB STAFFORD: What do police think happened inside your father's office?
JON CORNBLEET: Well, they know that there's a huge struggle just basically because a lot of things in the office were knocked around. There were a lot of broken chairs and whatnot.
ROB STAFFORD: Your father fought back?
JON CORNBLEET: My father fought back. My father was 64 years old, but he was in great shape. He was in really good physical condition.
But in the end, the attacker was able to overpower and stab him to death. More than 20 wounds were found on his body. It was a vicious attack, but why? His office wasn't ransacked; nothing was stolen, not even cash.
ROB STAFFORD: Did your father have enemies?
JON CORNBLEET: No, he didn't have any enemies.
ROB STAFFORD: Could you think of anyone who would have done this?
JON CORNBLEET: No.
ROB STAFFORD: And did you go through every name you could possibly think of?
JOCELYN CORNBLEET: There wasn't anyone to go through. He wasn't a shady character. He didn't do drugs. He wasn't having affairs. He wasn't that kind of person. There was not one person we could think of who could do that. I mean we assumed it would be a patient because that would be the only person that could make sense. But he didn't have complaints. There wasn't people that were suing him. So we didn't have anybody to point a finger at.
But police had a lot of clues to work with: Physical evidence left at the scene and videotape from the building security cameras, which showed a young man walking in and out - a man the security guard had seen.
ROB STAFFORD: What do you see on the tape?
JON CORNBLEET: I just saw a young man trying to conceal his identity, walking into the building very suspicious-looking just in how he was ducking away from the cameras. And then when you see him leaving, it's very evident that, you know, something had occurred.
ROB STAFFORD: Are you convinced that man on the tape is the man who killed your father?
JON CORNBLEET: Yeah - we were convinced of it right away.
ROB STAFFORD: Right away?
JON CORNBLEET: Right away, yeah. Somebody actually rode down the elevator with the young man and she described him as being very suspicious. He was breathing very heavily, trying to cover up his face, had blood on his shoes, which she thought was very peculiar. Blood was coming out of his nose.
The man on the tape appeared to know exactly what he was doing, carefully concealing his face from the camera.
JOCELYN CORNBLEET: He wears different hats as well.
ROB STAFFORD: He goes in wearing one hat and comes out wearing a different one?
JOCELYN CORNBLEET: Right. He also uses some kind of tissue or handkerchief when he pushes open the door and when he touches the elevator button to push it - so as not to leave fingerprints so it definitely made him more suspicious.
JON CORNBLEET: This was a carefully-plotted murder, that this was somebody who went in there with the intention to kill him.
ROB STAFFORD: You think your father was targeted.
JON CORNBLEET: Definitely.
ROB STAFFORD: How often do you think about what must have happened?
JON CORNBLEET: I think about it everyday. What went down there and what the struggle was like. What kind of pain he was in, what his last thoughts were 'cause it's got to be bizarre. You know, there you are in your own office ready to help people and this maniac comes in there with a knife trying to hurt you.
The killer left behind DNA and an unusual but unused hardware store item. The police won't tell us what it is, but that item, along with its packaging, seemed to be useful evidence for detectives to work with.
DAN DRUCKER: They came in pretty confident that they thought would catch the person - that it was somewhat of a sloppy crime, if you will.
And again they had that surveillance tape - so they knew the man they were looking for was young, white, blond and about 6 feet tall.
ROB STAFFORD: Do you think that police will solve this quickly?
JON CORNBLEET: I thought it was gonna be very quick.
But two months later, there was no arrest, not even a suspect. Then there was a possible break: It turns out that unusual hardware item the killer left behind was sold only at Home Depot stores. Police were reviewing store security tapes when they spotted a man who seemed to look familiar, buying that unusual item three and a half weeks before the murder.
JON CORNBLEET: This person was the only one who matched the description and this person only bought this particular item, which is kind of a peculiar item. That's what prompted police to say, “The detectives really wanna talk to this person.”
The police released the video to the media with a plea to the public to help find the man.
ROB STAFFORD: You're convinced the guy on the tape at Home Depot was the man that killed your dad.
JON CORNBLEET: Yeah, I was convinced of it.
Two pieces of tape of a man the Cornbleet family and the police thought were one and the same. But even with the release to the public of both tapes, the crime remained unsolved. A new investigative tool was needed -- so the family turned to MySpace.
Images from surveillance tapes at a high-rise building and at a Home Depot store were the best evidence so far in the search for the man who'd viciously stabbed Dr. Cornbleet to death in his own office. But weeks into the investigation, Chicago police still had no idea who the killer was.
ROB STAFFORD: What are police telling you about the investigation?
JON CORNBLEET: That it's very slow, it's very complicated, very complex. And, you know, here we have a mountain of forensic evidence, we have witnesses, we have surveillance tapes. Yet, we can't figure out who this person is.
ROB STAFFORD: Are you getting frustrated?
JON CORNBLEET: I'm getting very frustrated by it.
JOCELYN CORNBLEET: I think the police were as well. It wasn't your typical crime.
And Jon, Jocelyn and her fiance, Dan Drucker, began to believe the crime would not be solved in a typical way... So they asked themselves, where would you look for a 20-something suspect? And that's when Dan, who works in marketing, came up with an idea.
JON CORNBLEET: Dan says to me, "I think we need to use tools that the assailant and his friends would be on - those being MySpace, YouTube, things like that. The typical 20 to 25-year-old really isn't gonna be watching the news or reading the traditional media newspapers.
ROB STAFFORD: So you decide to target the peer group of the killer.
DAN DRUCKER: Basically the strategy was that I think everybody thought the best information was going to come from his peers. So at that point I told Jon that we have to get online. I wanted to put it within an arena where by the nature, people are searching for, connecting with and just spreading information - and MySpace really was the best way to do it.
They posted a flyer on MySpace along with the police phone number and they paid to have the surviellance tape from the office and Home Depot enhanced, which they uploaded onto the Web.
DAN DRUCKER: Just by the nature of the site, you're - you're able to connect with people, invite them to be your friends and if they end up being your friends, they're actually connected to your site. So you can communicate with them in various ways. But even if they decide not to be your friend, they'll still be exposed to your site. So it's almost like handing a flyer to someone.
Right away the response was overwhelming.
DAN DRUCKER: Once Jon and I were on the site inviting friends, we would be getting 30 to 40 friend requests every single day. And they would send it off to their friends, all throughout the nation. It was phenomenal, the response we got.
At first, most of the responses were condolences from people who knew him, like this one:
“I visited your father once about 6 or 7 years ago to get some warts removed from my arm. He was a very kind and gentle man and I can't wait until this fiend is caught.”
“I wish I could identify this man. Pray that u find him soon.”
There were also ideas and suggestions offered about trying to identify the hats he was wearing, questioning whether he could be a courier or messenger, predicting the killer was a college student living near the Home Depot the tape came from.
All were appreciated by the Cornbleets, but none led anywhere.
ROB STAFFORD: How did the police react to what you were doing?
JON CORNBLEET: Anything to help the case, they were pro. And they thought, "Hey, this is really different," something they had never dealt with before, but they were pretty receptive to it.
Jon also put up flyers around the city, especially near the Home Depot where the unidentified man bought that peculiar item like the one left at the crime scene. As time passed, Jon became even more convinced this was the man who murdered his father.
JON CORNBLEET: 'Cause, I thought, “If it was me and I recognized myself and I know what stores I purchased what at, I would have cleared my name immediately.” And when that didn't happen within a month, then I thought to myself, "This has to be the right person."
ROB STAFFORD: You put the picture out.
JON CORNBLEET: We did.
ROB STAFFORD: And you're pushing hard.
JON CORNBLEET: We're pushing --
ROB STAFFORD: -- to get answers.
JON CORNBLEET: Correct.
ROB STAFFORD: You wanna find the guy on that tape.
JON CORNBLEET: Correct.
Then, finally, the man on the Home Depot tape came forward.
JON CORNBLEET: He called the police and said, "I'm the guy and I don't even know who this doctor is. - I need to turn myself in over this. We need to clear this."
It turns out this young man had a reason for making the purchase and a clear-cut alibi for the time of the killing.
ROB STAFFORD: Did the man on the Home Depot tape have anything to do with your father's death?
JON CORNBLEET: No, absolutely not.
After all that, the Home Depot lead was a dead end. It was a big disappointment, but the family's MySpace Website was about to pay off. Around the same time, their page had received a mysterious e-mail in the wee hours of April 12, six months after the murder of dr. David Cornbleet.
JON CORNBLEET: The subject was, "Jonathan, do not delete." And obviously I read it and just by the tone of the email and what he wrote in there and how sincere this person sounded, I knew that this was a pretty accurate lead right away.
In fact, it'd be the lead they'd been waiting for -- and it was a shocker.
Six months after vowing to find his father's killer, Jon Cornbleet woke up to find an email he was urged not to delete. A man in New York had something he needed to say.
JON CORNBLEET: It basically says that "I'm a Marine and I don't wanna get your hopes up, but I believe that I have information pertaining to this case." And then he attempted to lay out where he was from, where he went to college, what infantry he was with, so it looked very, very sincere and very compelling.
The Marine had also contacted the Chicago police.
JON CORNBLEET: A Marine isn't gonna call the police and give them phony information.
But what would a U.S. Marine just home on leave from Iraq - know about the murder of a doctor in Chicago a half year earlier? Jon wanted to speak with him and asked the Marine to call him.
JON CORNBLEET: My phone rings at about 12:00 that afternoon. I just knew by the tone of his voice, by how much information that he had, I knew that this was very, very accurate.
In this email to Dateline, the Marine, who wants to remain anonymous, describes seeing a friend who was scared, timid and not himself. When the Marine asked him what was wrong, he simply said: "I think my former roommate killed someone."
According to the Marine, his friend said the man had been one of his roommates for most of 2006 in an apartment in New York City's upper east side. The friend described the roommate as "increasingly anti social, manic, prone to isolationist behavior, often staying awake for days"... And he threatened to harm a doctor who said he had done him wrong.
Then in October 2006, the roommate abruptly left New York for several days, then returned, packed a suitcase and left again. About two weeks later, the Marine's friend heard about Dr. Cornbleet's murder, "put two and two together" and had what he called "a gut feeling that something evil had gone down."
Most important, though, the friend had the name of the man he thought was the killer.
JON CORNBLEET: The name is Hans Peterson.
ROB STAFFORD: Had you ever heard that name before?
JON CORNBLEET: No, I had never heard that name before.
ROB STAFFORD: Jocelyn?
JOCELYN CORNBLEET: No, never.
ROB STAFFORD: Dan?
DAN DRUCKER: No.
But Chicago police were able to match the name immediately to the list of Dr. Cornbleet's patients. Hans Peterson had seen the doctor five years earlier. The question was, did Peterson's DNA match the DNA at the murder scene? Peterson no longer lived in New York, in fact, the Marine said he no longer lived in the country, but the marine knew the address of his former apartment. So detectives flew to New York, they went to the apartment looking for DNA, and they found it on a cigarette butt.
ROB STAFFORD: Did the DNA match?
JON CORNBLEET: It was a match.
Peterson was no longer in New York, but the ex-roommate did have a forwarding address for Peterson, which the Marine gave to police: It was in the Caribbean island of St. Martin in the French West Indies.
JON CORNBLEET: He knows every single aspect about where this person is right now.
ROB STAFFORD: You think this case is solved.
JON CORNBLEET: Essentially, yes.
So did the police. Armed with evidence, including the surveillance video and a DNA match, they issued an international arrest warrant. But there were still two big questions in the case. One: would the long arm of the law be able to grab him in the Caribbean?
JOCELYN CORNBLEET: We just assumed that our government - the FBI would speak to the officials in St. Martin, explain the situation, show the evidence. They would come in and arrest him and send him back to the United States because the evidence was just so overwhelming. This is what my brother and Dan had been working for - for months to achieve. And we were gonna obtain justice for my dad.
The second question: could there be any kind of defense for such a savage murder? An expected answer to that question would come from the suspect's own father.
ROB STAFFORD: You seem to be blaming the victim.
THOMAS PETERSON, Hans Peterson’s father: Who are you calling the victim?
Hans Peterson had fled the country to the island of St. Martin in the French West Indies. Back in his home state of Oregon, his father, another doctor named Thomas Peterson, watched the high-rise surveillance tape for the first time.
ROB STAFFORD: You look at that security camera video and what do you see?
THOMAS PETERSON: I see that is him walking in and out of there - yeah.
ROB STAFFORD: Your son?
THOMAS PETERSON: Yes.
ROB STAFFORD: Did your son kill Dr. Cornbleet?
THOMAS PETERSON, Hans Peterson’s father: I believe so.
Dr. Cornbleet lived his life by the ticking of a clock. And Hans Peterson, too, seemed to have a clock ticking in his life, nut in his case it may have been counting down to disaster.
The father says Hans, who played football as a boy, was once full of promise. He describes him as extremely bright as a child but socially awkward.
THOMAS PETERSON: There was a lot going on in his head, but he didn't always verbalize it much. But everyone liked him.
His son's shyness became a problem as he got older.
THOMAS PETERSON: He would very rarely initiate a conversation. He wouldn't often speak more than a few sentences at a time.
ROB STAFFORD: Were you worried about it?
THOMAS PETERSON: It just was who he was. Around age 15 or 16, you know, when social life became more important and he became a bit depressed, you know, we took him to the doctor, he got on anti-depressants, and his depression seemed to be somewhat cyclical. It would kind of come and go.
ROB STAFFORD: Did the medication help?
THOMAS PETERSON: It seemed to help. It seems to smooth out the bumps in the ride. I don't think it really, you know, makes the problem go away.
ROB STAFFORD: Must have been difficult for you as a dad to see him struggle.
THOMAS PETERSON: Yeah, it's always hard to see your children struggle.
After graduating from the University of Wisconsin with a double major in economics and philosophy, Hans eventually took a job as an options trader in Chicago in 2002. Concerned about an acne problem, that spring he picked Dr. Cornbleet out of a phone book and made an appointment -- an appointment that would change many lives.
ROB STAFFORD: May 2002, what happens?
THOMAS PETERSON: I get a call from him saying, "I took this acne drug and I am feeling horrible. I'm very depressed, I can't think straight. I have a terrible headache, I have this horrible noise in my ears. I need to come home."
ROB STAFFORD: What did you say?
THOMAS PETERSON: “I'll get you a ticket to come home tomorrow, pack your stuff up and stick it somewhere and we'll worry about it later.”
Hans told his father the cause of his dramatic decline was Accutane, the drug Dr. Cornbleet had prescribed him. It comes in various doses, but Hans told his father he was prescribed the highest one - two 40 milligram pills - that he took for two days. Hans says Dr. Cornbleet told him to take both pills at the same time rather than separately during the day as recommended.
THOMAS PETERSON: He called Dr. Cornbleet when he started getting the headaches and Dr. Cornbleet told him to stop the medication.
ROB STAFFORD: Did your son go back to see Dr. Cornbleet?
THOMAS PETERSON: I don't believe so.
Hans flew home to his father, who says he was stunned by the son he saw.
THOMAS PETERSON: He's very agitated. There was a look of torment in his eyes, but yet his eyes were vacant, you really couldn't contact him. And he was holding his head in pain.
ROB STAFFORD: Had you ever seen him like this before?
THOMAS PETERSON: Never. This was nothing like his depression. He was in pain. You couldn't look in his eyes and have a human to human conversation about anything.
ROB STAFFORD: And what does that feel like for you?
THOMAS PETERSON: It feels like I lost my son.
ROB STAFFORD: Did you call Dr. Cornbleet?
THOMAS PETERSON: No.
He took Hans to various doctors for help and says a psychiatrist diagnosed Hans as psychotic and prescribed Zoloft, an anti-depressant.
Still, despite his problems, Hans took the law school admission test and did so well, he received a scholarship to a law school in New York, where he enrolled in January 2003.
ROB STAFFORD: Does he continue to take anti-depressants?
THOMAS PETERSON: Yes.
ROB STAFFORD: How does he get them?
THOMAS PETERSON: He would get them off the Internet at times. And at times, I would get a desperate phone call from him saying, "I'm out of Zoloft, can you call in a prescription?" I would tell him, "You need to have a psychiatrist there at the school taking care of you. I will get you enough for two weeks."
ROB STAFFORD: Did your son see a psychiatrist?
THOMAS PETERSON: I don't believe he did.
As graduation approached in the spring of 2005, Hans stopped returning his father's phone calls.
THOMAS PETERSON: So I left him a message saying, "I'm gonna call the police for a missing person." So he calls and then tells me that he had not been going to classes and had officially taken a leave of absence a month ago. And he is now become an online gambler. When his depression is under control, he's doing very well, and when his depression is bad, he's not playing.
For another year, his father says Hans continued to live in New York City, gambling online as his job, and rarely socializing... still obsessed with Accutane and the doctor who prescribed it.
Then, in October 2006, according to Jon Cornbleet, Hans rented a car in New York and drove 800 miles to Chicago. Using a false name, he called and made an appointment with Dr. Cornbleet for 4:45 p.m. - the last appointment of the day - on Tuesday, October 24.
Jon told us what he understands happened next. Hans Peterson went to Chicago to teach the doctor a lesson and took with him a tool bag for torture: carrying a rope, duct tape, pliers, a hacksaw, knife, even a small blow torch. His plan was to cut off the doctor's hands and feet and use the blow torch to cauterize his limbs. But the plan went wrong when the doctor fought back, so Hans stabbed him to death.
Two months later, in late December 2006, Hans moved to St. Martin, where he lived alone in this upstairs apartment, without raising suspicion - until early August 2007, when he found out the FBI was closing in. Then he abruptly walked into a police station and confessed to French authorities that he murdered Dr. Cornbleet. He was taken into custody.
Even knowing all that, Hans's father believes his son is not solely responsible for the brutal killing.
ROB STAFFORD: Who do you blame for Dr. Cornbleet's homicide?
THOMAS PETERSON: It's a combination of factors. I would blame Roche Pharmaceuticals for having this drug on the market in spite of all the horrendous things that have happened. I would blame the FDA for allowing them to keep it on the market. I would blame Dr. Cornbleet for giving it to him.
He says his son's acne was not bad enough to be given such a powerful drug, with warnings of possible serious side effects, psychiatric ones. Because of these possible side effects and others, the drug is controversial, its warning insert says doctors should prescribe Accutane for only the most severe cases of acne. But because it's so effective, dermatologists commonly prescribe it for all kinds of acne.
So is Accutane dangerous?
DR. DOUGLAS BREMNER, PSYCHIATRIST: I'm very concerned about this drug.
Hans' father referred us to this man, Dr. Douglas Bremner, a vocal critic of the drug, who is a psychiatrist and radiologist at Emery University in Atlanta.
BREMNER: There's a number of cases in the literature of suicide and behavioral changes. Not a week goes by that I don't hear of another case reported to me, just from friends and family.
Dr. Bremner conducted a study on accutane that claims the drug may affect a part of the brain involved with depression - and can be very risky for some patients.
DR. BREMNER: I think that it has effects on the brain that can lead to psychiatric side effects like depression, suicidality, changes in behavior, including violence and aggression.
Dr. Bremner has never met or evaluated Hans Peterson, but he thinks Accutane could have contributed to Hans killing Dr. Cornbleet.
ROB STAFFORD: Is this a good case of cause and effect?
BREMNER: I don't think that you can definitely say that that was the sole cause of this homicide.
ROB STAFFORD: Can you even say for sure that Accutane, the drug, had anything to do with this homicide?
BREMNER: I think it did contribute in some way because it caused the psychiatric side effects.
But his work on Accutane has its critics. His study was very small and funded by people suing Roche over the drug. And though Dr. Bremner is an expert witness in some Accutane cases against Roche, one judge recently barred his testimony, questioning whether he was providing "personal opinion or true science."
Roche, the maker of Accutane, expresses its sympathy for the Cornbleet family, but adds this case is about murder, not the drug. Accutane, it says, has been used by millions of people worldwide and is safe and effective. Although the package does carry warnings about psychiatric events and violence, the company says numerous studies have found no cause and effect relationship between Accutane and those events, rare reports of violence, or sexual dysfunction.
ROB STAFFORD: You're blaming this murder on a drug your son took four and a half years before this attack even happened, and he only took the drug for two days.
THOMAS PETERSON: Right, 'cause it damaged his emotional brain.
ROB STAFFORD: You seem to be blaming the victim.
THOMAS PETERSON: Who are you calling the victim?
ROB STAFFORD: Dr. Cornbleet.
THOMAS PETERSON: Don't you think Hans is a victim? There's two victims here and each family's gonna call their own the primary just because that's what people do with families.
ROB STAFFORD: Dr. Cornbleet is dead.
THOMAS PETERSON: Hans is essentially never gonna be a functioning member of society again. There are multiple victims and multiple villains. And I feel that one of the victims is Dr. Cornbleet and one of the villains is Dr. Cornbleet. One of the victims is Hans Peterson; one of the villains is Hans Peterson.
Hans's father says his son spoke with attorneys about filing a malpractice lawsuit against Dr. Cornbleet, but no one wanted to take the case. Besides, he echoes what his son wrote online in July 2007.
THOMAS PETERSON: So what? So you file a lawsuit. Read his blog. It says, "Their lives will go on with just a little less money. Our lives will never be the same." And you know, I think there's a lot of truth in that.
Hans' father says his son went another way and exacted his own justice.
THOMAS PETERSON: It was his way to avenge what happened to him. His life was destroyed by Accutane and Dr. Cornbleet was the agent who supplied it. So this was vigilante justice, in his mind.
If Hans took the law into his own hands, the question would soon become: would the law get its hands on Hans?
JOCELYN CORNBLEET: I don't think anyone could have predicted what would happen next.
Hans Peterson says he stabbed Dr. David Cornbleet to death, and his father blames it on a drug and the doctor who prescribed it.
Dr. Cornbleet's family is offended and angered by that notion.
JOCELYN CORNBLEET: To slander him and say that he, with intent, tried to do something horrible to his son makes me sick.
JON CORNBLEET: To me, everything with the Accutane is a lot of smoke and mirrors. If there were any substance to this, he would have filed a proper lawsuit or complained a couple years back.
Dr. Bennett Leventhal is a psychiatrist at the University of Illinois in Chicago and an expert in psychopharmacology, the study of drug-induced changes in mood, thinking and behavior. He says psychological problems associated with Accutane are anecdotal and not scientifically proven. Like Dr. Bremner, he also has never met Hans Peterson, but he says Hans appears to have had serious problems before he ever took Accutane.
ROB STAFFORD: Do you think Accutane aggravated the problems Hans already had?
DR. BENNETT LEVENTHAL, PSYCHIATRIST: I think it's quite possible that in the days after he took Accutane for the first time and only time, that he may had had an aggravation of his symptons. But after three, four, five, six days, Accutane was gone, and I think probably played little role in what transpired in the subsequent four or five years.
He also says while Hans may be mentally ill, accutane most likely had nothing to do with that -- or the murder of Dr. Cornbleet.
ROB STAFFORD: Hans' father said he saw a night and day difference in his son after he took this drug. And he said that that dose was a shock to the system that changed his son's life forever.
LEVENTHAL: He's a man who desperately cares about his son and is desperately concerned that something terrible happened to his son to cause him to murder somebody. Something terrible probably did happen to his son, but it probably isn't Accutane.
If Accutane isn't the cause of his problems over the last several years, what was? At one point, Hans himself wrote a description on another Website of his childhood and personality traits, raising another possible explanation for at least some of his complaints.
In February 2007, just a few months after the murder, he wrote that he's "always been different from most," that he was so uncommunicative many "felt he was mute" and he has "never been in a real relationship in his life." He wondered whether he has Asperger's, a mild form of autism, a brain development disorder characterized by extreme social awkwardness.
There was no mention of Accutane or the doctor he'd obsessed about for years, a doctor who was already dead.
By the time Hans wrote that, he was in St. Martin in the Caribbean's French West Indies. Why did he go there? Well, Jon Cornbleet says when Hans confessed down there, he said he wanted to avoid being prosecuted in the United States. In Illinois, if convicted of premeditated murder, he would face life without parole. Under French law, if sentenced to life, he could be paroled anytime after 22 years.
For now, French authorities are keeping him in jail while they decide whether to formally charge him with murder and try him in a French court, because France does not extradite its citizens.
Why does this apply to Hans Peterson? Well, it turns out, his mother is French, which means he has dual citizenship and can take advantage of St. Martin's favorable sentencing laws.
DAN DRUCKER: I guess in his mind, whatever punishment he would get in France wouldn't be enough for him to really feel that as punishment.
In fact, when he confessed to the murder of Dr. Cornbleet in August, Jon Cornbleet says someone who witnessed Hans being taken into custody said Hans did not appear upset.
JON CORNBLEET: From what I understand, he was actually smiling. He thought it was hilarious. He thinks that he basically got away with one.
ROB STAFFORD: Is he right?
JON CORNBLEET: In a sense so far, yes, he has.
BERNIE MURRAY, prosecutor: You have an American citizen murdering an American citizen and only then, when he wants to look for maybe a lesser sentence or maybe more lenient treatment in a French courtroom, does he flee to France and exercise his rights under his dual citizenship.
Bernie Murray is the lead Illinois prosecutor on a case he may never get to try. But he is trying to get Hans Peterson extradited back to the states, although French law is making that highly improbable.
MURRAY: It's incredibly frustrating. I've tried all sorts of cases for over 20 years. I've never seen a situation like this where a crime was committed right here in the heart of Chicago, where all the evidence that will be related to this case comes from either Chicago or nearby and what we see is a foreign country saying, "No, we'd like to try him in our country." It's bizarre.
In fact, due to a treaty agreement, prosecutor Murray has had to assist the French in preparing their case against Hans Peterson. He did so under protest.
MURRAY: To tell me that it's gonna be tried in the small West Indies Island merely because of the person's heritage through his mother, well, you might as well be telling me that we're trying the case in the Twilight Zone.
While he fights for extradition along with the Cornbleet family, who have the support of their Senators Barack Obama and Dick Durbin as well as the State department, Hans' father feels his son would receive better treatment from the French than in the states, so he's glad he fled to St. Martin. As his son sits in a Caribbean jail, not yet formally charged and no plea entered, he's out defending him. But despite Thomas Peterson's unbending belief, his son was damaged by a drug and a doctor, he did say this.
THOMAS PETERSON: I want the Cornbleet family to know that they have our deepest sympathy and condolence for the loss of Dr. Cornbleet. It was a very horrible way that he died and my heart goes out to the family.
And his feelings about his own son are as dark as they come.
THOMAS PETERSON: Suicide would have been better than this.
ROB STAFFORD: Really?
THOMAS PETERSON: At least no one else would have got hurt. And his misery would have been ended.
ROB STAFFORD: That must be a very difficult thing to say.
THOMAS PETERSON: Yeah.
JOCELYN CORNBLEET: I can't imagine what he's going through knowing that he raised this individual, trying to stick up for his son after he's done this.
The Cornbleets are now focused on getting Hans Peterson extradited back to the states, even translating their MySpace page into French.
JON CORNBLEET: I think getting justice in the United States and having him prosecuted, yes, I definitely think it would bring some sense of closure to me.
A father fighting for his son, a son fighting for his father, as the wheels of justice move slowly... for the man who was always on time.
JON CORNBLEET: I've lost my best friend. I've lost my mentor in life. So my life will never be the same, but I do want justice for him and I want it in our country.
ROB STAFFORD: Anything you wanna say to Hans Peterson?
JOCELYN CORNBLEET: He's hiding like a coward. He did it, face it. He confessed to it. It's time to serve your time for doing what you did.
French authorities were in Chicago in January and spoke with the Cornbleet family, local prosecutors and others as they research the case.
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