ERIE — A woman pleaded not guilty Tuesday to accusations that she was behind a bizarre bank robbery plot that ended with a pizza deliveryman being killed by a bomb locked around his neck.

Marjorie Diehl-Armstrong's public defender, Thomas Patton, entered the plea on her behalf and said she understands the charges filed against her last week.

Federal prosecutors on Wednesday charged Diehl-Armstrong, 58, and Kenneth E. Barnes, 53, with bank robbery, conspiracy and a firearms violation in connection with the Aug. 28, 2003, robbery of a PNC Bank in Summit Township.

Barnes, who was already jailed in Erie County on unrelated drug charges, pleaded not guilty last week.

Pizza deliveryman Brian Wells, 46, told police he had been forced at gunpoint to wear a time bomb around his neck and rob the bank. The device exploded while officers waited for the bomb squad to arrive, killing Wells.

Diehl-Armstrong is serving seven to 20 years in the Muncy prison after pleading guilty but mentally ill to killing her boyfriend, James Roden, in 2003.