LACKLAND AIR FORCE BASE, Texas -

An Air Force staff sergeant being tried by general court martial as part of a growing Lackland sex scandal pleaded guilty to some counts against him but said he is not guilty of sexually assaulting a female basic training student.

The federal case against Staff Sgt. Kwinton Estacio, of the 331st Training Squadron, kicked off Monday morning at Joint Base San Antonio.

The military training instructor pleaded guilty to violating lawful general regulation, violating a contact order and obstruction of justice but pleaded not guilty to sexually assaulting a female airman.

He will face a trail by a jury composed of military officers. 

According to court documents, Estacio allegedly coerced a female Airman into engaging in a sexual acts with him, using his military authority to make her believe it would negatively impact her military career if she didn't cooperate.

The case is just the latest in a growing sex scandal at Lackland. 

Investigators say more than a dozen female recruits were sexually assaulted or harassed by male instructors at the base.

"There are allegations of inappropriate conduct at present or and or contact with trainees against 17 military training instructors. One has been convicted of rape thus far. Two have been convicted of unprofessional relationships," said Joint Base San Antonio spokesman Brent Boller. 

The case against Estacio is the fourth court martial case at Lackland so far, with more in the foreseeable future.