Lewis was a community leader in East Palo Alto and co-founded a nonprofit called Free at Last, which provides substance abuse treatment and transitional housing.
San Mateo police spokesman Lt. Mike Brunicardi said investigators are still working "tirelessly" on the case.
With the approval of David Lewis' family, San Mateo police chief Susan Manheimer asked that a state reward be offered to encourage individuals with information about the crime to contact law enforcement officers.
"We greatly appreciate the prompt actions of Gov. Schwarzenegger, who today issued a $50,000 reward upon our request," Manheimer said in a statement. "We believe that this reward will help generate critical leads."
Manheimer said she believes information from the community will help police solve the crime.
The governor's office has offered 265 rewards since the program began in 1967, and 20 of those have been paid, Schwarzenegger spokeswoman Rachel Arrezola said.
To be eligible for such an award, a law enforcement chief must put in a written request and have approval from the victim's family.
Anyone with information about the shooting is asked to contact the San Mateo Police Department by calling the investigations team at (650) 522-7650; calling dispatch at (650) 522-7700; leaving an anonymous tip at (650) 522-7676; texting an anonymous message to (650) 262-3473; or emailing an anonymous message to firstname.lastname@example.org.