The victim, identified by the medical examiner's office as 37-year-old Sean Moffitt, had gone home and told his roommate he was attacked at about 9:30 p.m. on Oct. 28 in the 1500 block of Haight Street, police spokesman Officer Gordon Shyy said.
The victim told his roommate that several people had surrounded him and hit him in the head multiple times with a metal object, police said.
Police are still investigating the circumstances of the injuries.
Moffitt went to sleep that night, but the next morning the roommate noticed his injuries were worse and called 911. Paramedics took him to San Francisco General Hospital, where he succumbed to his injuries on Oct. 30, according to the medical examiner's office.
Police are considering the case a suspicious death as they await the results of Moffitt's autopsy, Shyy said.
No arrests have been made in the case.