Washington (CNN) -- A Pennsylvania woman convicted in a bizarre bank robbery that involved a pizza deliveryman with a bomb attached to his neck lost her Supreme Court appeal on Monday.
The justices, without comment, turned aside claims from Marjorie Diehl-Armstrong that she was innocent and mentally incompetent to stand trial.
Diehl-Armstrong, 63, was convicted of conspiracy and other charges related to the death of pizza deliveryman Brian Wells in 2003.
Authorities said Wells walked into a PNC Bank branch in Erie, Pennsylvania, on August 28, 2003, with a pipe bomb locked around his neck, and gave the teller a note demanding money. The robbery netted about $8,700.
Wells was killed when the bomb detonated as he sat in a parking lot after being stopped by police.
The case drew national attention and was the subject of an intense investigation.
Questions arose initially about whether Wells was a willing participant or a murder victim.
Prosecutors have long contended that Wells was involved in planning the robbery, but balked when he realized the bomb was real. They said he was threatened with a gun to make him wear it.
"I am not a crazed killer," she said at her sentencing. "The true killers are still out there."
A federal appeals court rejected her appeal in November.
Diehl-Armstrong's case was delayed because she underwent treatment after the judge in the case found initially that she was mentally incompetent to stand trial.
A third suspect was sentenced to 45 years in prison and a fourth died shortly after the robbery of a drug overdose, officials said.