Philip Bondy's devotion to apotemnophilia, a sexual fetish he shared with a handful of people in the world, cost him his life. The 79-year-old New Yorker died of gangrene after he had his healthy right leg amputated below the knee.

Bondy paid a former doctor, John Brown, £6,250 to cut off his leg. Apotemnophiliacs get sexual gratification from the removal of limbs. But the operation went wrong and two days later Bondy died in a San Diego hotel room.

Brown, 77, has been found guilty of second-degree murder and faces a life sentence. He is to be sentenced next month.

He lost his medical licence in 1977 after three patients almost died from sex-change operations he performed in a garage and a hotel. He was sent to jail in 1989 after another botched sex-change operation.

His lawyer told Brown's latest trial, at San Diego superior court, that his client had never intended to kill. "No help for the weirdos," Sheldon Sherman said. "That's the problem. Not John Brown. Not his surgical techniques. Their problem is there's no help for the weirdos except for somebody like John Brown."

Mr Sherman said Brown had spent decades helping those on the fringes of society. "He took a segment of society no one cared about. No one else would deal with transsexuals. Did he do this for money? No. He did it because he cared."

But the prosecutor, Stacy Running, said: "Phil Bondy is dead because John Brown cared? He doesn't care, he takes advantage."