Jack Kevorkian, the zealous, straight-talking doctor known as “Dr. Death” for his lifelong crusade to legalize physician-assisted suicide, died Friday at a hospital in Royal Oak, Mich. He had pneumonia and kidney problems. He was 83.

Kevorkian spent decades campaigning for the legalization of euthanasia. He served eight years in prison and was arrested numerous times for helping more than 130 patients commit suicide between 1990 and 2000, using injections, carbon monoxide and his infamous suicide machine, built from scraps for $30. Those he aided had terminal conditions such as multiple sclerosis, malignant brain tumors and amyotrophic lateral sclerosis, also known as ALS or Lou Gehrig’s disease.

When asked in a 2010 interview by CNN’s Anderson Cooper about how it felt to take a patient’s life, Kevorkian said: “I didn’t do it to end a life. I did it to end the suffering the patient’s going through. The patient’s obviously suffering — what’s a doctor supposed to do, turn his back?”

Dying should be an intimate and dignified process, which many terminally ill are denied, he said.

He garnered a fair amount of support from other medical practitioners, but most believed he was an extremist. In 1995, a group of doctors in Michigan publicly voiced their support for Kevorkian’s philosophy stating that they supported a “merciful, dignified, medically assisted termination of life.”

Shortly after, a study in the New England Journal of Medicine found that many doctors in Oregon and Michigan supported some form of doctor-assisted suicide in certain cases.

One of his greatest victories was in March 1996, when a U.S. Circuit Court of Appeals in California ruled that mentally competent, terminally ill adults have a constitutional right to die with the aid of medical experts and family members. It was the first federal endorsement of its kind.

But ultimately Kevorkian’s impact was not on the American legal system but in raising public awareness about euthanasia and the suffering of the terminally ill.

In the 1990s, the peak of his time in the limelight, he tried publicity stunts of all sorts to draw attention to his cause, showing up at one trial dressed in colonial attire. His face was constantly on television and in newspapers, and he shared his views through a barrage of media interviews. His crusade and antics were documented in a 2010 HBO film, in which Al Pacino portrayed him as a passionate but intolerably single-minded crusader.

“He was involved in this because he thought it was right, and whatever anyone wants to say about him, I think that’s the truth,” said Arthur Caplan, a professor of bioethics at the University of Pennsylvania. “He didn’t do it for the money, he didn’t do it for the publicity, he wasn’t living a luxurious life — he wanted change.”

His goal was to make it legal for a doctor to actively help a patient commit suicide. But no state has yet made this legal and only three states, Washington, Oregon and Montana, have legalized any form of physician-assisted suicide. Michigan, where Kevorkian did much of his work, explicitly banned physician-assisted suicide in 1993 in direct response to his efforts.

“I think Jack Kevorkian was like a flare on the battlefield — he lit up the issue and everyone paid attention,” Caplan said. “He got to absolute center stage, but he didn’t have the nuance to take it forward the way he wanted to.”

Kevorkian was born May 28, 1928 in Pontiac, Mich., to Armenian immigrants. He wanted to be a baseball radio broadcaster but his parents advocated a more practical path. He graduated from the University of Michigan’s medical school in 1952 and began a residency in pathology, and a peculiar obsession with death.

In the 1950s he received the nickname “Dr. Death,” when he began photographing patients’ eyes to determine their exact time of death.

And then, as a pathology intern facing the sorrowful faces of terminally ill patients, he became convinced that euthanasia had a place in the medical profession.

“Euthanasia wasn’t of much interest to me until my internship year, when I saw first hand how cancer can ravage the body,” he wrote in his 1993 book “Prescription Medicine: The Goodness of Planned Death.” Afterward, he was entirely devoted to the cause.

To aid him in committing suicide, he often used his homemade machine that sent a saline drip into a person’s arm intravenously. When patients wished to die, they could press a button that would trigger the release of a potent chemical that would put them to sleep. One minute later, a timer on the machine would administer a dose of potassium chloride that would cause the heart to stop.

Kevorkian faced trial four times in Michigan. He was acquitted in three instances because of unclear laws on the legality of physician-assisted suicide; the fourth was declared a mistrial.

Unlike Michigan, most states still do not have explicit laws banning physician-assisted suicide, and Kevorkian was almost always careful not to administer the fatal medication himself, though it was his hope that eventually the law would allow him to do so. Thus he was long able to escape prosecution.

But he was arrested and convicted in 1998 after recording his assistance in the suicide of Thomas Youk, who was too ill with ALS to administer the drugs himself.

Kevorkian did it for him and allowed the recording to be aired on the CBS News television show “60 Minutes.”

Soon after, he was found guilty of second-degree murder. During the trial, he vehemently denied wrongdoing.

The prosecutor “calls it a murder, a crime, a killing,” Kevorkian said. “I call it medical science. Tom Youk didn’t come to me saying ‘I want to die, kill me.’ He said ‘Please help me.’ There was medical affliction. Medical service is exempt from certain laws.”

Kevorkian was sentenced to 10 to 25 years in prison but was paroled in June 2007 for good behavior after promising not to assist in any more suicides.

Kevorkian said his belief regarding a patient’s right to die was in the Constitution, unwritten but guaranteed by the Ninth Amendment, which states that Americans are not excluded from rights that are not specifically enumerated in the constitution.

“There have been many constitutional scholars over time that have believed that the Ninth Amendment deserves more respect, but Dr. Kevorkian took it further than most lawyers and most constitutional scholars would take it,” said Alan Dershowitz, a Harvard professor and lawyer who was an adviser in several of Kevorkian’s legal battles.

“He was part of the Civil Rights movement — although he did it in his own way,” Dershowitz said.

“He didn’t lead marches; he didn’t get other people to follow him. Instead, he put his own body in the line of fire, and there are not many people who would do that. In the years that come, his views may become more mainstream.”