A British tourist who was hospitalized for more than a month after being stabbed in the head during a robbery in San Francisco has died, police said.

San Francisco Police Officer Albie Esparza said 48-year-old Paul Tam of Manchester died Thursday at San Francisco General Hospital, where he was taken after the Feb. 18 attack.

Esparza told the San Francisco Chronicle that Tam was walking with his niece when he was attacked by a couple. Tam attempted to hold onto his messenger bag but was stabbed in the head by the male suspect. His niece was not injured.

Security video released by police showed the attacker chasing Tam onto a street, stabbing him while he was on the ground and taking his bag before running away.

Police have yet to make an arrest in the attack, which is now being investigated as a homicide.