L.A. County Sheriff Robert Luna said, “We are actively collaborating with multiple agencies abroad to provide assistance in the search for Deputy Calibet and will use every resource we have available to bring him back to those who love him.”

He added that his thoughts and prayers are with Calibet’s family.

Calibet, an experienced hiker who has visited Amorgos for years, disappeared Tuesday after failing to return from a hike.

Greek officials are searching for him, including several agencies and volunteers from the Greek coast guard along with teams from neighboring islands of Paros and Naxos.

A drone is being used in the search.

British TV presenter Michael Mosley went missing days before Calibet. Mosley’s body was found four days later on the Greek Island of Symi.

Calibet’s girlfriend Debbie Leshane arrived in Greece Friday.

“He called me right before he was leaving for the hike. … It was 7:07 [a.m.] in Greece, and then we spoke six minutes, and then he sent me a picture at 9:20 [a.m.] at the trail head with the sign. And we have not spoken since,” LaShane said.

Calibet’s brother Oliver said the family is staying very positive, but on the fourth day time is of the essence in the search.

Calibet’s sister-in-law Sandrine Cutright said, “He’s physically fit. He swims every day, he runs.”