Washington, Jul 22 (IANS): An air force instructor has been sentenced to 20 years in prison for rape and sexual assault in a scandal that has rocked one of America's busiest military training centres, Xinhua reported Sunday.

Sgt. Luis Walker was sentenced Saturday after a military jury at Lackland Air Force Base found him guilty on charges of rape, aggravated sexual contact and multiple counts of aggravated sexual assault.

Military officials said the initial flirtations Walker directed at the women he trained at the base grew into something more sinister -- threats and intimidation that eventually led to rape.

Walker was among 12 trainers investigated in the sex scandal at the base in San Antonio, Texas.

The alleged crimes occurred between October 2010 and June 2011, according to the US Air Force.

Walker was the first to stand trial in the scandal. Six of the instructors have been charged and face charges ranging from rape to adultery.