PALO ALTO (CBS SF) — It’s been 10 days since a flight instructor from Palo Alto vanished while flying over the Pacific Ocean.

Security cameras at the Palo Alto Municipal Airport caught 24-year-old flight instructor William James McAdams allegedly taking a plane from the school where he worked without permission on May 8. He then flew out of the airport around 1 a.m. to an unknown destination, according to police spokesman Sgt. Brian Philip.

Police are tracking a wide area off the coast of Watsonville where a ping from the plane, a 2011 G1000 Skyhawk 1TG with tail number N191TG, was last detected at 2:45 a.m.

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What happened to the pilot and the plane after the late-night flight remains a mystery.

“We’ve been looking for any sign of evidence of what may have happened to this plane,” Phillip said. “I’ve been working with various local agencies, federal agencies, the military.”

McAdams has been a flight instructor with Advantage Aviation since 2012. No one from the company wanted to speak on camera about his disappearance, but investigators say they’ve tried unsuccessfully to track the plane.

Phillip said its possible McAdams may have traveled as far south as Mexico.

“We have not found found anything significant to suggest that he is in one particular location,” Phillip said. “This isn’t an easy investigation because we don’t have people in planes go missing all the time.”

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Back on the ground, investigators say the trail has gone equally cold. No phone calls, social media posts or financial activity to give them any clue to where McAdams might be.

Detectives say they’ve contacted virtually every airport between Palo Alto and Mexico, looking for any sign of the missing pilot and plane.

McAdams does face potential theft charges, but the police department and family say their highest priority is simply figuring out where he might be.