By Carey Gillam

(Reuters) - Missouri is set to execute on Tuesday a man who along with a friend abducted, raped and stabbed to death a 15-year-old girl in 1989.

Roderick Nunley, 50, is scheduled to be put to death by lethal injection at 6 p.m. (7 p.m. EDT) in the state's death chamber in Bonne Terre, Missouri.

Nunley pleaded guilty to the murder of Ann Harrison, a Kansas City high school girl who was waiting for her school bus on a March morning when he and accomplice Michael Taylor drove by and decided to kidnap and rape her. After assaulting her, the two men stabbed Harrison multiple times and left her body in the trunk of a car they had stolen.

Taylor also pleaded guilty, and was executed in April 2014.

As Nunley's execution date has neared, his lawyers and the Missouri Attorney General's office have inundated courts with claims and counterclaims over whether the execution should proceed.

In an appeal to the U.S. Supreme Court, lawyers for Nunley argued among other things that the death penalty constitutes "cruel and unusual punishment."

Less than an hour before the scheduled execution, the Supreme Court said it was denying a stay of execution.

Janel Harrison, the victim's mother, said she and her husband, Bob Harrison, were looking forward to gaining some closure.

"For the past 26 years there have been times when Bob and I have felt compassion for Nunley, Taylor and their families only to remember how frightened Ann must have been," Janel Harrison said.

"The total fear she felt when she was bound and unable to defend herself while listening to them discuss how they were going to kill her. The pain she felt when they stabbed her, not once, but at least 10 times. That is the true definition of unusual pain and suffering. The only closure that our family will have is knowing that justice for Ann has been attained and that we are finally through with the judicial system."

Nunley was previously set to be executed in October 2010 but the execution was delayed to address an appeal raised by him challenging the imposition of a death sentence by a judge and not a jury.





(Reporting by Carey Gillam in Kansas City, Missouri; Editing by Mohammad Zargham and Sandra Maler)