SAN DIEGO (AP) — A Marine was charged Tuesday with murder and dereliction of duty in the death of a detainee in Fallujah, Iraq, after authorities say his involvement came to light during a lie-detector test for a job with the Secret Service.

Sgt. Ryan Weemer is the third person charged in the case, which centers on allegations that a Marine squad shot a group of unarmed captives during heavy fighting in November 2004.

The case arose when Weemer, 25, applied for a job with the Secret Service. Investigators claim Weemer described the killing during a polygraph test that included a question about whether he had participated in a wrongful death.