Petty Officer First Class Russell Matthews returned home Sunday night, police said. Police say he was incoherent and taken to a hospital for observation.
Coast Guard spokesman Lt. Gene Maestas said the service doesn't know where Matthews, a Hawaii-based rescue swimmer, has been and what he's been doing since his wife reported him missing on Oct. 9.
Coast Guard investigators dispatched to see him confirmed his identity after he called his command from Castle Medical Center in the Honolulu suburb of Kailua, Maestas said. He's now being evaluated at Tripler Army Medical Center in Honolulu.
Coast Guard investigators looking into his disappearance won't question him until he's released by doctors, Maestas said. But the service will probe the incident.
"We'll try to find out why he disappeared and all the details surrounding his case," he said.
Police found the 36-year-old guardsman's car abandoned at Kaena Point, a remote area of Oahu, when Matthews was reported missing in October.
Crews from the Coast Guard, Navy, state, county lifeguards and Honolulu fire and police departments together searched more than 10,000 nautical square miles—on land and at sea—for Matthews. The search was called off on Dec. 13.
Honolulu Police Sgt. Kim Buffett
The police case is closed now that Matthews has been found, she said.
It's unusual for a Guardsman to go missing for months and then reappear, Maestas said.
"This is not the norm for the Coast Guard. In my 28 year career in the Coast Guard, I have never come across a case like this," he said.
Matthews, an aviation survival technician, has been in the Coast Guard for 15 years. He's been assigned to Hawaii since 2007.