Rockville High School senior Michelle Miller was found dead in the Germantown home of a U.S. Army sergeant who helped recruit her. He shot Miller and then killed himself, according to Montgomery County police. (Courtesy of WJLA)

The Army has launched an internal investigation into the relationships between an Army staff sergeant and young recruits after he killed a 17-year-old soldier-to-be and then himself, officials said Wednesday.

Staff Sgt. Adam Arndt, 31, shot Rockville High School senior Michelle Miller, 17, before killing himself this week, police said. Friends of Miller told law enforcement officials that the two were romantically linked, all while Arndt was married to another former army recruit who enlisted at the same Gaithersburg station where he worked.

The investigation aims “to assess whether we could have predicted that Staff Sergeant Arndt was going to do something like this,” said Brian Lepley, an Army recruiting spokesman. “It will include his interaction with all future soldiers at the recruiting station.”

Arndt was a former mentor for aspiring soldiers while Miller participated in the program’s training sessions at his Gaithersburg station, army officials said. Miller was planning to begin basic training for the U.S. Army Reserves this summer, according to her father.

Arndt married his wife, Kaitlyn, last June, her family said; the 21-year-old soldier is currently serving in North Carolina. The Army said it had no further information about Kaitlyn Arndt’s military service.

Michelle Miller (Courtesy of Rockville high school)