Christer Pettersson, 57, whose conviction for the 1986 killing of Prime Minister Olof Palme was overturned on appeal, died Sept. 29 at a hospital near Stockholm. He had been in a coma since Sept. 16 and died of a brain hemorrhage and organ failure.

Mr. Pettersson was unconscious when he was admitted to the hospital with severe head injuries, a hospital spokeswoman said. It was unclear what caused the injuries. He underwent surgery but never regained consciousness.

A convicted criminal with a history of substance abuse, Mr. Pettersson was the only person tried in Palme's slaying after being identified by Palme's widow, Lisbet, as the killer.

Palme was gunned down in downtown Stockholm on Feb. 28, 1986, as he walked home from a movie theater with his wife. Palme had campaigned against the Vietnam War and South Africa's apartheid system.

Mr. Pettersson was convicted of Palme's killing in 1988 but was acquitted on appeal after police failed to find the weapon.

The killing, which stunned Sweden, remains unsolved.

In 2001, Mr. Pettersson admitted to a Swedish writer that he shot Palme. "Sure as hell it was me who shot [him], but they can never nail me for it. The weapon is gone," he said in an interview with Gert Fylking.

He later retracted the statement and said he was not involved in the killing.

In 1998, the Supreme Court rejected a prosecutor's appeal to retry Mr. Pettersson, ruling that the evidence was not strong enough despite claims that Mr. Pettersson could be placed at the scene of the shooting on a busy downtown Stockholm street.

Christer Pettersson's conviction in the 1986 slaying of Swedish Prime Minister Olof Palme was overturned.