Air Force instructor handed 20 year sentence for abuse July 21, 2012 -- Updated 1937 GMT (0337 HKT) An Air Force instructor has been convicted of rape and aggravated sexual assault He was implicated in a sex abuse scandal involving 10 female recruits Walker is among 12 instructors investigated for sexual misconduct Six face charges in the scandal (CNN) -- An Air Force instructor convicted of rape, aggravated sexual assault and other charges against 10 female recruits was handed a 20-year prison sentence Saturday in a military scandal that spurred investigators to examine the extent of the abuse. Staff Sgt. Luis Walker was convicted Friday after being investigated on accusations of sexual abuse against his female subordinates while he was assigned to the 326th Training Squadron at Lackland Air Force Base in the San Antonio, Texas, region. Walker will be reduced to the lowest enlisted rank, be dishonorably discharged and forfeit all pay and allowances, according to a Lackland statement Saturday. He is among 12 instructors investigated for sexual misconduct against at least 31 trainees, and one of six to face charges in the scandal. The commander of Air Force training earlier named Maj. Gen. Margaret Woodward to head a two-month inquiry, covering all four Air Force bases that handle basic training, which are located in Texas and Mississippi. At Lackland, one trainer had earlier pleaded guilty to having an improper relationship with a trainee, as part of a plea agreement. Staff Sgt. Peter Vega-Maldonado was sentenced to 90 days in prison, 30 days hard labor and a demotion in rank and pay. In his plea deal, he provided testimony against two other trainers who have been charged. He also said he had inappropriate relationships with 10 trainees. Last year, the Defense Department recorded more than 3,000 cases of sexual assault throughout its branches. Defense Secretary Leon Panetta in April announced plans to create a special victims unit to investigate and prosecute allegations of sexual assault. CNN's Elwyn Lopez contributed to this report