Casper, 63, vice president of the San Francisco Civil Service Commission, was jogging along the south edge of eastbound River Road west of Wilshire Drive when he was struck by a truck around 7 p.m. on Aug. 14.
Witnesses said the truck slowed down, then fled east on River Road.
Casper's family and friends determined to find the person responsible in the hit-and-run announced Monday they are offering a $10,000 reward for information leading to the arrest and conviction of the driver.
The CHP has released a photograph of the truck taken by a surveillance camera at Korbel Champagne Cellars at 13250 River Road moments before Casper was hit.
The truck is a newer model white Ford F-150 with an extended cab and possibly a gold stripe along the bottom, the CHP said.
Anyone with information about the truck or anyone who has noticed friends, acquaintances or coworkers who have stopped driving their Ford F-150 should call CHP Detective Mike Phennicie or Sgt. Robert Mota at (707) 588-1400.
