Family members of a missing Fox executive and sheriff's department investigators announced a $20,000 reward Tuesday for information in the case.
Gavin Smith, 57, was reported missing after leaving a friend's residence in the Oak Park area on the night of May 1.
"We believe that the Los Angeles County Sheriff's Department and these detectives are doing everything they possibly can to find him," wife Lisa Smith said during a news conference to announce the reward.
"We need additional tips, and we're hoping the public can provide those," Smith said.
Witnesses told NBC4 that they saw Smith May 7 at a popular restaurant in Morro Bay, but those tips did not pan out.
"We investigated it thoroughly, top to bottom," LA County Sheriff's Department spokesperson Steve Whitmore said. "It was cleared, meaning that it was not Gavin Smith, regrettably."
The black 2000 Mercedes 420E in which Smith left the Oak Park area residence had a padded storage roof rack and California license plate 6EKT044.
The sheriff's department says it is using all resources, including a fix-winged aircraft, to try and find Smith. Some people fear Smith's car may have gone off the side of a canyon road, making it difficult to find.
A website, FindGavinSmith.com, has been started to draw attention to the case and Smith's siblings met with media in Reno, Nev., on May 16 to issue a plea to their brother.