MIAMI (CBSMiami/AP) – A former Orlando area man who has been on Florida’s death row for more than two decades for the rape and murder of a young girl is scheduled to be executed Wednesday evening.

Barring any last minute stays, Elmer Carroll, 56, will be put to death by lethal injection at 6 p.m. at the Florida State Prison in Starke.

During his two decades on death row, Carroll’s lawyers have argued that he’s too mentally ill to stand trial or be subjected to the death penalty.

In November 1990, Carroll was indicted on a count of first-degree murder and sexual battery for the rape and strangulation of 10-year-old Christine McGowan. The girl lived with her family next door to a halfway house for homeless men where Carroll was staying in Apopka.

Carroll, who had been imprisoned twice for indecent assault on a child, had told one of his housemates that the girl was “cute, sweet and liked to watch him make boats,” according to witness testimony at his trial.

Christine’s stepfather found the girl dead in her bedroom and his truck was missing. The truck was found a short time later and an officer came upon Carroll — who had blood on his sweatshirt and genitals, while traces of his semen, saliva and pubic hair were found on Christine, according to court records.

Carroll’s lawyers employed the insanity defense at his trial, during which they and prosecutors presented conflicting testimony from psychiatrists about Carroll’s mental competency.

A final petition to stop the execution is pending before the U.S. Supreme Court. The petition says that Carroll should have been considered mentally ill at the time of the murder.