Updated 11/28/11 – 3:55 p.m.

CHICAGO (CBS) — A killer finally has been brought to justice in the brutal murder of a Chicago doctor, stabbed to death in his Michigan Avenue office more than five years ago.

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Hans Peterson was the suspect in the killing of Dr. David Cornbleet in his dermatology office across the street from Millennium Park in 2006

Peterson, who was captured on video entering Cornbleet’s office building at the time of the stabbing, fled to the French-controlled island of St. Martin after the attack.

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Because Peterson’s mother is a French citizen, authorities there refused to extradite him on murder charges.

After a long legal battle, a court in the nearby island of Guadalupe convicted Peterson last Friday of first-degree murder. Peterson was sentenced to life in prison.

“It’s a sense of relief I feel that we did everything we could to get justice for my father,” said Dr. Cornbleet’s son, Jonathan. “But the pain is still there.”

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He also talked about what it was like to see his father’s killer in court last week.

“It’s tough, to be honest with you. I mean, he showed no remorse, showed no compassion, didn’t care,” Jonathan Cornbleet said.

“In a sense, it’s brought a sense of closure, it still hurts though,” he added. “I mean, you know, you’ve lost your father in the most traumatic way and, you know, having to spend Thanksgiving down there was very, very hard.”

Jonathan Cornbleet said his family now has justice after Peterson’s conviction. He said that, during the trial, Peterson stunned everyone by giving a blow-by-blow account of how he carried out the crime.

“He got up and basically said that his lawyer … is not accurate. He knew what he was doing, he concealed his face, he is very proud of what he did and that he needs to go to jail and not to an insane asylum,” he said.

Peterson had said Dr. Cornbleet prescribed him an acne medication that made him impotent and he wanted revenge. Jonathan Cornbleet said it was revealed in court Peterson had an obsession with Dr. Cornbleet, having called his office more than 500 times.

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Peterson has filed an appeal and it’s possible his case could be tried again next year.