Spc. Christopher Dombroski, 20, had visited the site of the landslide near Oso several times to assist with search and recovery efforts, said Capt. Cynthia Holuta of the Army's 7th Infantry Division at Joint Base Lewis-McChord.
He was the nephew of Steve and Theresa Harris, who are listed among the missing in the landslide, Holuta said.
Dombroski, whose hometown was listed as Wasilla, Alaska, had been missing since Sunday night in the Capitol Forest near Olympia. Thurston County search teams found him dead of an apparently self-inflicted gunshot wound Tuesday morning, said Lt. Greg Elwin, a spokesman for the Thurston County sheriff's office.
The death remains under investigation by the Grays Harbor County sheriff's office and coroner, because Dombroski's body was found in Grays Harbor County.
Dombroski joined the service in August 2011 and worked as a Stryker systems maintainer, the Army said. He served on one overseas deployment to Afghanistan from November 2012 to July 2013.
"Our thoughts and prayers are with Spc. Dombroski's family and friends during this time of loss," Lt. Col. Joseph Sowers, 7th Infantry spokesman, said in a written statement.