TUCSON, Ariz. (CBSDFW.COM/AP) — A medical examiner says two soldiers helping secure the Mexico border in Arizona died by suicide.

The body of Pfc. Kevin Christian was found June 23 in Ajo, about 120 miles from Tucson. The Pima County Medical Examiner said the 21-year-old from Haslet, Texas died from a self-inflicted gunshot wound.

Christian was an infantryman with the 2nd Battalion, 4th Infantry Regiment, 3rd Brigade Combat Team, 10th Mountain Division assigned to Fort Polk, La.

Christian was the second soldier found dead while on assignment along the southern border this month. Pfc. Steven Hodges, 20, of Menifee, California, died June 1 near Nogales, about 60 miles south of Tuscon. His death was also ruled a suicide by the ME.

Military officials say the circumstances of the deaths are under investigation.

About 2,400 service members are assigned to the border mission.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)