Jack Kevorkian, internationally known as 'Dr. Death' for his assisted suicide advocacy, passed away at 83 at a Detroit hospital on Friday.

Kevorkian had been battling kidney and heart problems, according to the Detroit free press. His attorney, Mayer Morganroth, said it appears Kevorkian suffered a pulmonary thrombosis when a blood clot from his leg broke free and lodged in his heart. "It was peaceful, he didn't feel a thing,

Kevorkian spent eight years in prison after being convicted of second-degree murder in the death of the last of the more than 100 terminally ill patients whose lives he helped end.