"Dr Death" was also convicted of "delivering a controlled substance", the potassium chloride used for the injection. He was released pending sentencing, which was set for 14 April.
Kevorkian, who had insisted on conducting his own defence - but re-appointed his lawyers shortly before the verdict - admitted administering the fatal drugs, but fiercely justified his action. Mr Youk was in the last stages of the muscle-wasting Lou Gehrig's disease, and the doctor protested that he had done his professional duty in relieving his suffering. Mr Youk had twice signed documents consenting to assisted death.
The prosecution, however, argued that the case was "not about the right to die" but about "Jack Kevorkian's right to kill". And with the doctor, who has no legal training, defending himself, the trial veered between high drama and chaos. His request to call Mr Youk's wife and brother to testify about his physical and psychological state was refused, and he had to rely on his closing argument to the jury.
"Just look at me," he pleaded. "Do you see a murderer? If you do, then you must convict. And then, take the harsh judgement of history, and the harsher judgement of your children and grandchildren if they ever come to need that precious choice." The prosecutor, John Skrzynski, responded by accusing him of coming to the Youk house "like a medical hitman in the night, with a bag of poison to do his job".
This was the fifth time in the past 10 years that Kevorkian, a retired pathologist, had stood trial for helping terminally ill people to die, but this was his first conviction. In three of the earlier cases he was acquitted, and he benefited from the declaration of a mis-trial in the fourth. This case, however, was also the first time that he was proved to have administered the fatal injection himself.
The main evidence was a videotape Kevorkian had recorded of Mr Youk's last hours, including the fatal jab. In a challenge to the judicial authorities, he had passed the tape to the CBS network, which incorporated an edited version into its current affairsprogramme, 60 Minutes, in November. It caused an outcry and left the authorities with little choice but to charge Kevorkian with murder.
Oregon is the only US state where assisted suicide is legal and pressure is growing for legalisation in other states. It was pointed out during the trial that Kevorkian's conduct in Mr Youk's case would be against the law even in Oregon, where strict safeguards apply.