Hans Peterson was sentenced to life in prison following a trial on the French-controlled island of Guadeloupe.
Dr. Cornbleet's family fought to make sure justice was served in the case. They traveled to the French Caribbean for the trial.
For many months after the doctor's murder, the Cornbleet family wondered whether the killer would be caught. Then came a tip, followed by a DNA work-up on a discarded cigarette butt which pointed to a suspect. But, by then the suspect had already fled the country for a Caribbean island governed by French law, which meant no extradition.
But there was a trial, and now the suspect, Hans Peterson, is looking at life in prison.
Peterson's face was not visible on the surveillance video as he walked out of 30 North Michigan. On the 12th floor, long-time dermatologist Cornbleet lay dead -- stabbed over 20 times.
Months would pass before a break in the case and some determined police work led investigators to Peterson, a one-time Cornbleet patient who had fled the US for the French-held Caribbean island of St Martin.
Last week, in a French court on the neighboring Island of Guadeloupe, Hans Peterson went on trial.
"I think that all my family was worried that the French wouldn't take the case seriously. They took it extremely seriously. Our prosecutor did a wonderful job," said Jonathan Cornbleet, the victim's son.
Jon Cornbleet, his sister and their mother all testified at the trial, after first hearing Peterson's own chilling recount of his detailed plan to assassinate the doctor. Peterson had blamed his own deep depression on a brief use of the drug Accutane, which Cornbleet had prescribed years earlier.
As for the murder, Peterson at trial said he had no regrets.
"Once everything happened it was a huge sense of relief to him and he was proud of it. No remorse, never an apology from him to his family or mine, anything like that," said Jonathan Cornbleet.
In the weeks and months that followed his dad's murder, it was Jonathan Cornbleet, and his family, who were determined to keep the case in the public eye. And, in part because of that, there was a break, then a suspect, then a confession, a verdict and a life sentence.
While it didn't happen in a US court, it is a life sentence nonetheless.
"It's brought a sense of closure," Cornbleet said. "It still hurts though having my dad murdered in such a dramatic fashion, and having to spend Thanksgiving at the trial, it was hard...It was a long, long week and I'm glad it's over."
Peterson has been in custody since he turned himself in to French authorities four years ago. His defense that he was influenced by the drug Accutane was apparently not convincing to the French jurors, who were told that Peterson took only a very small quantity of the drug some four years before the murder.
Though Peterson confessed to the crime, he is said to be appealing the life sentence.