When Coast Guardsman Russell Matthews’ car was found by police abandoned at a Kaena Point parking lot in a remote area of the Hawaiian island of Oahu, the fire department as well as the Coast Guard launched an all-out search.

U.S. Coast Guard

Petty Officer First Class Russell Matthews, 36.

Searchers scoured the north and south shores of the point. The fire department sent out helicopters and the Coast Guard deployed MH-65 Dolphin helicopters of its own. The Coast Guard Cutter Galveston Island, an HC-130 airplane and even a Navy P3 Orion aircraft joined in the effort for the missing 36-year-old man. Some 1,200 square miles of the tropical island and its surrounding waters were searched.

Police told a local TV station the aviation survival technician, a petty officer first class from Air Station Barbers Point, was emotionally distraught. 

On Sunday, the 15-year Coast Guard veteran and father of two showed up at his wife’s Oahu home after nearly four months away. But nobody was home.

Matthews was incoherent and taken to a hospital for observation, Honolulu police said Tuesday, according to The Associated Press. And, as it turns out, Matthews was being investigated for illegal marijuana use at the time of his disappearance, Coast Guard spokesman Chief Warrant Officer Gene Maestas told the Honolulu Star Advertiser.

Military investigators will talk to him when he gets out of the hospital.

Maestas has said the Coast Guard doesn't know where Matthews had been or what he'd been doing since his wife reported him missing Oct. 9, the AP reported. Coast Guard investigators confirmed his identity after he called his command from Castle Medical Center in the Honolulu suburb of Kailua.

He's now being evaluated at Tripler Army Medical Center in Honolulu, according to the AP.

Maestas told the Advertiser that illegal drug use is an offense that could result in a Coast Guard member’s discharge.

Contacted by NBC News on Wednesday, Honolulu police spokesman Capt. Andrew Lum said he could only confirm that Matthews was “no longer a missing person.”

A person in the public affairs office for the Coast Guard in Honolulu said a request by NBC News for information would be forwarded to a superior officer.