U.S. Air Force Staff Sgt. Luis Walker was convicted in a military court Friday on charges that included rape, aggravated sexual contact, and aggravated sexual assault, according to the Associated Press. Walker was convicted on a total of 28 counts.

The result is a big victory for prosecutors, who allege 11 other flight instructors at Lackland Air Force Base also engaged in sexual misconduct with at least 31 female trainees.

Walker was charged with the most serious crimes and will be free until his sentencing hearing, which begins Saturday. He faces a dishonorable discharge from the military, and a possible sentence of life in prison, AP reported.

Walker was the first of the accused to stand trial. During their testimonies, witnesses for the prosecution said the staff sergeant sexually assaulted them on beds in his office while ignoring their pleas to stop. The women, who will remain anonymous because of their status as sexual-assault victims, also used their time on the stand to describe how Walker would enter their dorms and force them into kissing, touching, and intercourse.

All U.S. Air Force personnel receive their training at Lackland, which is located in San Antonio. Each year, about 35,000 airmen graduate and about one-fifth of that number are females. Meanwhile, 90 percent of the instructors are males.

During the last fiscal year, there were 3,192 military reports of sexual assault, although the Defense Department has speculated that only 13.5 percent of assaults were reported, so the true number of assaults could have been closer to 20,000. Antiwar.com wrote that only 8 percent of these 3,192 cases went to trial. The possibility exists that a victim might have to face her rapist every day, and that she may even be required to take orders from him.

Rape victims have reported in recent years that when they come forward with rape or sexual-assault allegations, it's common for them to receive psychiatric diagnoses followed by military discharges, CNN reported. The military often describes these women as emotionally unstable and higher-ups sometimes accuse women of having sex only to regret it later.

Military hospitals are forbidden to perform abortions, even when the women in question have been raped and can afford to pay for the procedures on their own, according to the Guardian.

A documentary called The Invisible War has alleged that 30 percent of enlisted women are sexually assaulted in their time with the military. Directed by This Film Is Not Yet Rated documentarian Kirby Dick, it also stated that servicewomen are more likely to be raped by fellow troops while fighting in Afghanistan or Iraq than they are to be killed by the enemy.