Police are investigating the death of a 26-year-old Portland man who died three weeks after he was found unconscious in the middle of the night on a Portland street.

Edward Okeny, 26, died Thursday at Maine Medical Center from an injury he sustained Oct. 21, police said.

A group of passersby spotted Okeny at 2:10 a.m. Oct. 21 lying on the ground near the corner of Cumberland Avenue and Anderson Street.

Police and an ambulance were called after it was determined he was bleeding from a head wound, police said. His wallet was found next to him with some of the items removed, police said.

The State Medical Examiner conducted an autopsy Friday and determined Okeny died of a head injury, but the examiner has not completed the report. It is not yet clear whether Okeny was attacked or was injured in a fall, said Deputy Chief William Ridge.

Police have not located any witnesses to what happened and Okeny did not regain consciousness in the hospital so police could question him, he said.

Police are reviewing video taken at two businesses Okeny was, including one he was at less than an hour before he was found. Police are trying to identify people at the businesses who might have been with Okeny or seen who he was with, Ridge said.