A 20-year-old sailor assigned to U.S. Naval Support Activity Souda Bay, Greece, was found dead in his barracks room Wednesday, seven weeks after he reported for duty, the Navy announced Friday in a news release.

Seaman Apprentice Daniel A. Diaz enlisted in the Navy on April 6 and reported for duty at NSA Souda Bay Branch Health Clinic on Oct. 20. A co-worker found Diaz in his room after he failed to report for work, according to the Navy.

The Naval Criminal Investigative Service is investigating Diaz’s death, the cause of which was unknown Friday, according to the release.

“Our thoughts and prayers are with his family and friends during this most difficult time,” Capt. Scott Hogan, NSA Souda Bay commander, was quoted in the release.

Diaz was assigned to Recruit Training Command and Navy Hospital Corps School at Great Lakes, Ill., prior to reporting to NSA Souda Bay. His home of record was Winnetka, Calif.