The death of a man near a Portland trail system last week has been ruled a homicide.

Police were called about 4:40 p.m. on Jan. 18 to a campsite at the end of Frederic Street, near the Fore River Parkway Trail System, where 36-year-old Nicholas J. Gardner needed medical attention, according to Maj. Robert Martin, a spokesperson for the Portland Police Department.

By the time officers arrived, Gardner was dead.

Martin said Thursday the Maine medical examiner’s office ruled Gardner’s death a homicide, but he declined to release the cause of death.

The death remains under investigation.

Anyone with information about Gardner’s death can call the Portland Police Department at 207-874-8575.

Correction: Police released an incorrect spelling of Nicholas Gardner’s last name. The story has been updated.