Alameda County sheriff's officials say they're now offering a $100,000 reward in the 2004 murder case of a man who was gunned down in his driveway.

Authorities say 19-year-old Mark Espinal was killed outside his home near San Leandro after he was dropped off by friends in the early morning of Feb. 3, 2004. Investigators believe his two attackers were marijuana dealers.

No one was ever arrested in the case.

In 2007, the governor's office added $50,000 to the existing $20,000 reward fund. Sheriff's spokesman Sgt. J.D. Nelson says officials were able to increase the pot this year, thanks to a $30,000 contribution by an anonymous donor.

Anyone with information is urged to call the sheriff's office.