Jack Kevorkian, the man known as "Dr Death" for helping the terminally ill to die, has said he had no regrets for conducting assisted suicide.
Jack Kevorkian with his "mercy machine" in 1991
"I knew what I was doing... I accepted the consequences because I had to do the right thing," he told the BBC.
Kevorkian, 79, was released from a US prison last week after serving eight years for second-degree murder.
Kevorkian claims to have helped some 130 people to die in the 1990s. He has pledged not to do this any more.
The former pathologist was given a 10-25 year sentence in the US state of Michigan in 1999.
He won an appeal based on his own failing health, but could go back to prison if he conducted further assisted suicides.
Practice 'going on'
Kevorkian was convicted of the murder by injection of terminally ill Thomas Youk.
A video of him dying was broadcast on television.
"My aim isn't to kill, my aim is to relieve the patient's anxiety, to relieve his paralysing affliction mentally," Kevorkian told the BBC's Today programme.
"I have no regrets in helping the suffering human. If I had regrets I'd be the biggest hypocrite.
"This is not done willy-nilly, it isn't not done because I have a whim and I want to do it immediately. No. It's done for the sake of the patient," he said.
Kevorkian said he believed at least "half of the doctors" in the US were conducting assisted suicide secretly.
Earlier this week, he said would dedicate himself to garnering support for assisted suicide. But he conceded that he was unlikely to succeed.
Kevorkian was among the most controversial and divisive figures in 1990s America, the BBC's Jeremy Cooke in New York says.
He claims to have assisted in some 130 suicides mostly in the Detroit area between 1990 and 1998.
Many assisted suicides were conducted using his so-called mercy machine, which delivered lethal amounts of drugs intravenously. Some were in the back of his Volkswagen van.
His methods alienated many. In 1998 he offered on a "first come, first served" basis the kidneys of a man he had helped to die.