PHILADELPHIA — The scheduled execution of a convicted murderer has prompted pleas for clemency from thousands of people who argue that he should be spared because he had been sexually abused by his victim.

The inmate, Terrance Williams, 46, is scheduled to be executed by lethal injection on Oct. 3 for killing a man after what his supporters say was years of being abused by the victim, as well as by a teacher and an older boy who first raped him when he was 6.

Mr. Williams was 18 in June 1984 when he beat to death Amos Norwood, 56.

Mr. Williams was also found guilty in a separate trial of third-degree murder, which does not carry the death penalty, for the killing in January 1984 of Herbert Hamilton, 50, who had made sexual advances toward him, according to court testimony. Mr. Hamilton was stabbed and beaten to death.

If the execution is carried out, Mr. Williams would be the first convict put to death involuntarily in Pennsylvania since 1962. Since reinstating capital punishment in 1978, Pennsylvania has executed only three people, all of whom asked for death after having exhausted their appeals.