Suffolk homicide detectives and New York State Attorney General Letitia James’ office are investigating the death of a Shirley man while in the custody of Suffolk police late Monday.

Quinn Harrison, 39, was being held in a cell at the Sixth Precinct in Selden following his arrest earlier in the day on two bench warrants and a drug charge, police said. A detention attendant saw Harrison lying on a bench in an awkward position at about 9:40 p.m. and notified a desk sergeant.

Officers administered CPR and applied an automatic external defibrillator, police said. First responders from Selden Rescue who were called to the precinct continued CPR and administered Narcan, which reverses opioid overdoses, police said.

Harrison was transported by ambulance to Stony Brook University Hospital where he was pronounced dead.

Under New York law, the Office of Special Investigation conducts a preliminary assessment in situations where police officers, correction officers and other law enforcement officials may have caused a death. If that office determines an officer may have caused a death, it launches a full investigation of the death.