Butler police are investigating the suspected drug overdose death of a 32-year-old city man.

Christopher Otto was pronounced dead Monday at Butler Memorial Hospital, where his girlfriend drove him after the apparent overdose at their home on the 400 block of Brown Avenue, authorities said.

An autopsy was performed later that night but a cause of death is still pending results of toxicology tests, which won't be available for several weeks, said Butler County Deputy Coroner Larry Barr.

Butler police Deputy Chief David Adam said police did not learn of the circumstances of Otto's death until Barr informed them. The hospital notified the coroner's office Monday.

Otto's 39-year-old girlfriend told hospital staff that she had tried to revive him with the opioid overdose reversal drug Narcan before she eventually drove him to the hospital, authorities said.

Adam said that police have been in contact with the Butler County District Attorney's Office about the case.

“It remains under investigation,” he said.

The Thompson-Miller Funeral Home in Butler is handling funeral arrangements. Services will be held Sunday.