A man charged with fatally shooting an Indiana police officer in the head in 2022 died Thursday at a state prison, authorities said.

Phillip Lee, 49, was being held at Pendleton prison while awaiting trial next year on murder and other charges in the death of Richmond Officer Seara Burton. He was found alone in his cell and unresponsive by correctional staff, state police said.

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Police did not release details. But Lee's attorney said he was suffering mental distress and killed himself.

"Phillip had very severe mental health issues. It wasn't something that developed in the last week or two," Denise Turner told The Associated Press.

Fort Wayne, Bloomington, South Bend crime

A man charged with killing an Indiana police officer has died at a state prison while awaiting trial. Authorities say Phillip Lee was alone in his cell and unresponsive early Thursday.

"We had a couple of mental health experts working with Phillip, but they can’t be there 24/7," Turner said. "The prison was not doing anything to help Phillip."

Greg Dunn, spokesman at the Indiana Department of Correction, said he could not comment.

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Burton, 28, was shot while assisting officers who had stopped Lee on his moped and suspected that he possessed drugs. She died a month later in September 2022. She had been a police officer for four years in Richmond, about 65 miles (105 kilometers) east of Indianapolis.

Turner said Lee lately had expressed remorse.