Maine's highest court on Tuesday rejected another appeal by a man sentenced to life in prison for killing a police officer.

The Supreme Judicial Court unanimously sided with a judge who turned down John Williams' request for a new trial on the grounds that prosecutors withheld evidence about an arresting officer’s disciplinary record.

It was the second appeal for Williams, who was accused of killing a deputy and stealing his police vehicle, triggering a massive manhunt in April 2018.

Williams’ attorney previously argued that arresting officers beat the defendant during his arrest and that Williams confessed to the killing out of fear he’d be beaten again.

The new appeal focused on a state trooper who was disciplined for failure to timely report another officer’s misconduct — a state police lieutenant who punched Williams.

The court said it's unlikely that the evidence would have changed the outcome of the trial, the court said.

Furthermore, the evidence would have impugned the credibility of a trooper whose testimony helped Williams by confirming he was struck twice while handcuffed, the court said.

Prosecutors say Williams was angry over his girlfriend’s arrest and wanted to avoid going to jail himself when he shot a Somerset County Sheriff’s deputy on April 25, 2018, in Norridgewock.

Cpl. Eugene Cole was the first law enforcement officer to be killed in the line of duty in nearly 30 years in Maine.