ROCKLAND, Maine — A 51-year-old Maine State Prison inmate went on trial for the second time Wednesday, accused of possessing a makeshift knife that was found after a fight in which another prisoner was stabbed.

Timothy Mooney is on trial in Knox County Superior Court on a charge of possessing prison contraband. He was not charged with the alleged stabbing.

Mooney was convicted once before of the possession charge after a jury trial in May 2011. The Maine Supreme Judicial Court overturned that conviction last spring, saying that testimony made by a prison investigator to jurors — that Mooney would have been charged with additional crimes if the victim of the assault had cooperated — created too much of an unfair prejudice against Mooney.

That led to the retrial which began with opening statements Wednesday morning.

Corrections officer Angela Smith testified Wednesday that she heard a commotion and saw one prisoner trying to push Mooney out of the other inmate’s cell. She said she called for backup and ran to break up what looked like a fight.

She said she saw Mooney make a downward motion with something in his hand that was directed at the other prisoner. She said she also sprayed Mace in the cell to break up the fight. She said she then grabbed Mooney by the back of his shirt and pulled him away from the other prisoner.

At that point, she said she saw something fly from Mooney’s hands and heard what sounded like metal hitting concrete.

She then found the other prisoner bleeding from wounds to his shoulder and wrist.

Dr. James Curtis, an emergency room physician at Pen Bay Medical Center in Rockport, testified that the prisoner had a cut to his wrist and a deep cut to his shoulder. The prisoner told the doctor that he had been stabbed.

Assistant District Attorney Christopher Fernald told jurors in his opening statements that the victim was not cooperative and that this is common after assaults within the prison.

He said there will be some circumstantial evidence but that jurors can place weight on that as well as direct evidence.

Defense attorney Thomas Shehan Jr. of Searsport told jurors that there were other people in the area where the fight occurred and that he believed the state could not prove its case beyond a reasonable doubt. Shehan had represented Mooney in his appeal of the first conviction.

The trial is expected to end Thursday.

Mooney is serving a 35-year sentence for the 1998 murder of former girlfriend Elizabeth Nelson-Blais. In 1998, Mooney was homeless and living in Portland. Police said he smashed the woman’s skull with a concrete block after the two had consumed vodka and orange soda in a metal shack.

Mooney had been sentenced to an additional three years for the May 2011 conviction but that was vacated because of the successful appeal.