Authorities are investigating how a Lawrence man died while he was in custody in a cell at the Lawrence Police Department headquarters, Essex County District Attorney Paul F. Tucker and Lawrence Police Head of Department Michael McCarthy announced Saturday.

Christian Marte-Martinez, 25, of 45 Fern St. was placed into the cell at 1:15 a.m. Saturday after being arrested earlier in the night.

About 5 a.m., police discovered Marte-Martinez unresponsive in the cell. They began CPR and other life-saving measures before he was transported to Lawrence General Hospital, where he was pronounced deceased.

The incident is under investigation by the Essex County District Attorney’s Office State Police Detective Unit and detectives from the Lawrence Police Department.