State police are investigating the death of a Maine State Prison inmate who died Tuesday night.

A Department of Corrections spokesman said the Alan Powell, 57, died at 6:30 p.m. at the state facility in Warren.

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Powell had served 22 years of a life sentence for murder, said spokesman Scott Fish.

The death is being investigated by the state police and the state Medical Examiner’s Office under the direction of the attorney general.

Fish said he could not provide more details about the incident.

State police spokesman Steve McCausland said nobody has been charged with killing Powell.