SAN ANTONIO » A sergeant charged with sexually assaulting female recruits at the Texas Air Force base where U.S. airmen go through basic training is a “consummate predator,” a military prosecutor told jurors Tuesday at the outset of the officer’s court-martial.

Staff Sgt. Luis Walker, who faces the most serious charges in a burgeoning sex scandal involving Lackland Air Force Base instructors, raped one female recruit and sexually assaulted or inappropriately had sex with nine others whom he was training, the prosecutor, Major Patricia Gruen, said in her opening statement today.

“He is a wolf in sheep’s clothing,” Gruen told the seven-person jury comprised of military personnel. 

Major Naomi Dennis, one of Walker’s attorneys, told jurors there is no evidence to substantiate the charges against Walker — 28 counts, including rape, aggravated sexual contact and multiple counts of aggravated sexual assault. He could get up to life in prison and a dishonorable discharge if convicted of the most serious charges.

“Ten victims, 28 charges. Those are just numbers. Numbers aren’t proof,” Dennis said.

Base officials have described Walker’s case as the “cornerstone” of an ongoing investigation into sexual misconduct in which 12 instructors, including Walker, have been charged or are being investigated. The charges range in severity from rape to adultery.

Investigators have identified at least 31 female trainees who they believe were victims in the sex scandal. A two-star general, Maj. Gen. Margaret H. Woodward, has launched a separate, independent probe, and nearly 80 members of Congress have called for a hearing of the scandal.