San Francisco police have doubled the reward to $150,000 for information that helps identify and bring charges against the person suspected of killing Mitchell Warren in the Tenderloin.

Warren, 24, was shot on September 30, 2016, after walking a friend home. Police say a stranger confronted him and shot him once after an altercation. Warren called 911 himself but died at a hospital. Wednesday marked 10 years since his death.

Surveillance footage showed the suspected shooter leaving on the handlebars of a bicycle. Police identified the cyclist, who said he did not know the shooter. Investigators have not located the suspect and believe he may live outside San Francisco or the Bay Area.

Warren had been working as an apprentice electrician. His father, Lary Warren, continues to seek answers. Police ask anyone with information about the shooting to contact the department.