A Coast Guard seaman accused in the strangling and beating death of a shipmate was "best buddies” with the victim and had struggled with him to keep him from swimming in frigid Alaskan waters, according to his lawyer.

Seaman Ethan Tucker, 21, appeared Wednesday in a preliminary hearing at Camp Pendleton, Calif. to determine if there’s enough evidence to go forward with a court martial. He faces murder, involuntary manslaughter, aggravated assault, obstructing justice and other charges in the death of 19-year-old Seaman Ethan Kelch. Both were assigned to the Kodiak, Alaska-based cutter Douglas Munro, which was awaiting repairs in Dutch Harbor when Kelch went missing during the evening of January 26.

Kelch, who was from Virginia Beach, was found unresponsive on the western side of Amaknak Island after a search that involved the Douglas Munro crew, an MH-65 Dolphin rescue helicopter and Unalaska police, fire and emergency services personnel. He was pronounced dead the next morning.

Investigators suspect that Tucker strangled and punched Kelch in the head — causing swelling between the skull and scalp — before placing his body in the water and leaving him to die, according to charge sheets provided to Navy Times. They also allege Tucker misled them about where to look for Kelch because he feared criminal proceedings, and that he also lied about an injury to his hand, the court filings state.

But Tucker’s military attorney, Navy Cmdr. Justin C. Henderson, told Navy Times in a telephone interview that his client and another seaman assigned to the cutter were out drinking “way too much."

They tried “desperately” to keep Kelch from swimming in water that was 38 degrees, Henderson said. He introduced Snapchat videos spanning a half hour that he said support the defense’s theory.

“He kept trying to run into the water when he had had too much to drink and they struggled with him for almost half and hour,” Henderson said.

Henderson said the videos show Kelch collapsed. He was found very late at night passed out about 200 yards away, he said.

The videos were not played in court Wednesday. They were taken by the third seaman, Trevin Hunter, who did not testify.

Henderson said Tucker’s cause of death was drowning and hypothermia. The method was undetermined.

Coast Guard legal spokesman Lt. Cmdr. Anthony De Stefano declined to discuss the case.

“The Coast Guard is committed to ascertaining the truth and pursuing justice and that includes receiving the opinions and recommendations that the preliminary hearing officer produces,” he said.

Tucker was transferred from the cutter and moved to Base Alamada, where his military attorney, Henderson, said he worked in base security until his arrest in August. He’s since been held in San Diego’s Naval Consolidated Brig Miramar.

Earlier this month, Henderson filed a petition with the Coast Guard Court of Criminal Appeals alleging Tucker was confined illegally.

Henderson said Kelch and Tucker were “two really great kids” and that the incident has “been tough on the whole crew.”

“Seaman Kelch was very well liked on the ship and so was Seaman Tucker,” Henderson said.

The hearing officer is expected to make a recommendation in the case by October 25.

UPDATE: In two paragraphs, the names of the defendant and alleged victim were mixed up. We corrected that.