DOVER, Del. (AP) - A former Dover Air Force Base reservist who impregnated a 14-year-old girl has been sentenced to four years in prison on child rape charges.

Thirty-four-year-old Staff. Sgt. Byron White received the minimum mandatory sentence Monday after pleading guilty in July to two counts of third-degree rape.

White was the fourth Dover airman to face child sex abuse charges in the past year.

MORE: Delaware Air Force reservist charged with raping, impregnating teen girl

An investigation began last December after someone complained on a Division of Family Services hotline.

White was arrested at the military base in February on nine counts of third-degree rape and continuous sexual abuse of a child. Authorities said White had been in a sexual relationship with his victim since May 2017.