A woman who says she wore a hidden microphone to help build a case against a Denver Women’s Correctional Facility canteen supervisor accused of sexually harassing and assaulting inmates has sued prison investigators because the man was not charged for groping her crotch during the sting.

“They used her as human bait and allowed her to be sexually assaulted while she was wearing a wire,” Denver civil rights attorney David Lane said Wednesday. “He disappears from the Department of Corrections, but no criminal charges are filed. Why wasn’t he charged?”

Late Tuesday, Lane’s law firm filed a civil claim in U.S. District Court in Denver on behalf of Susan Ullery, 32, against the former supervisor, Bruce Bradley; Rick Raemisch, the executive director of the Colorado Department of Corrections; Warden David Johnson; Capt. Ramona Avant; and two investigators.

The lawsuit accuses supervisors, including Raemisch, of “reckless and callous indifference” despite the prison having the highest rate of sexual assault of prisoners by correctional officers in the nation.

A spokesman for the state Department of Corrections did not return a request for comment Wednesday.

A review of state court records by The Denver Post found that Bradley, who resigned from the prison soon after the assault, has not been charged criminally for the alleged assault.

The Post typically shields the names of sexual assault victims, but Lane said Ullery wanted her name published as a message to fellow inmates.

“She wants to stand up as an example to other prisoners that they don’t have to put up with sex assault by guards,” Lane said.

Ullery, convicted of stealing nearly $20,000, on June 24, 2014, was sentenced to six years in the prison, where she worked in the canteen.

Bradley began sexually harassing Ullery about four months after she started work in the canteen, the lawsuit says.

His behavior toward Ullery escalated. Bradley began sneaking up behind Ullery while she was doing inventory in a storage area and pressing his groin against her buttocks, the lawsuit says. At first, he said it was a mistake but later moaned in her ear while doing so, the lawsuit says.

Ullery told Bradley that she was a lesbian so that he would stop. But he responded by suggesting that she should have sex with him and another woman, the lawsuit says. He began demanding that Ullery show him her breasts and threatened to punish her if she didn’t, it says. She reluctantly complied, the lawsuit says.

After learning that a member of Ullery’s family had died, Bradley suggested sexual activity to make her feel better, the lawsuit says. Another inmate overheard Bradley graphically describing how he wished to have sex with Ullery.

Repeated complaints to two other male canteen employees were ignored, the lawsuit says. The officers told her she should be glad he “liked her.”

One time after she complained, correctional officer David Wang suggested she put “Grandpa,” a reference to Bradley, in a good mood.

Wang also allegedly overheard Bradley threaten to write her up for disobeying a lawful order and suggesting she would “lose her parole” if she didn’t “masturbate for him.”

Witnesses reported that Bradley sexually harassed female inmates he supervised as early as 2008, the lawsuit says. Women had previously filed grievances against Bradley claiming sexual harassment and sexual assault. Bradley also “behaved inappropriately” with three other inmates, the lawsuit says.

Ullery met with investigators from the state Department of Corrections’ inspector general’s office, Avant and other prison officials in April 2016, the lawsuit says. When she told them that her complaint was against Bradley, one of them replied that they “assumed as much,” the lawsuit says. An investigator told her that every time an inmate accused Bradley, it became a “he said, she said” situation. They said they needed hard evidence against him.

They asked Ullery to wear a wire to record Bradley’s inappropriate behavior. She was reluctant, worrying that it would compromise her release on parole, which had already been granted, or that she would be branded a snitch or sent to solitary confinement for her last three months in prison.

But the investigators argued that she would be sparing other women the same abuse she suffered and promised to intervene before any sexual assault could take place, the lawsuit says.

On April 26, 2016, investigators wired Ullery and sent her to work in the canteen. Bradley immediately paged her to his office. When she arrived, he immediately demanded she show him her breasts, but no investigators intervened. He then chided her for being reluctant to masturbate in front of him, the lawsuit says. Investigators again failed to respond, the lawsuit says.

“What is wrong with you?” Ullery asked Bradley. Visibly angry, he walked around his desk, backed her into a wall and groped her crotch, the lawsuit says. The investigators left her alone with Bradley for three minutes before a sergeant entered the office.

When Ullery met with investigators later, they told her the device was not initially transmitting well.

Bradley was placed on paid administrative leave on April 27, 2016, and he resigned in lieu of being fired on May 31, 2016, the lawsuit says. He had worked for the corrections department since 1993.

Other inmates learned through the rumor mill that Ullery caused Bradley to be fired and began threatening to beat her up or kill her, the lawsuit says. Bradley had been popular with some inmates, the lawsuit says, because he was willing to bend — or even ignore — rules.

She asked to be placed in solitary confinement for her protection. Ullery wrote dozens of kites, an institutional name for prison letters and grievances, which were disregarded during her last three months in prison, the lawsuit says.

Ullery continues to suffer flashbacks about the assault and takes medications for anxiety and post-traumatic stress disorder, the lawsuit says.

The prison has a history of sexual assault, the lawsuit says. In 2009, the state was ordered to pay another inmate $1.3 million for her being raped and coerced into sex acts, the lawsuit claims.

After the lawsuit, CDOC installed 200 surveillance cameras in the prison and instituted reforms that cut sexual assaults of prisoners from 66 in 2008 to 19 in 2012, prison officials have said.

Despite the reforms, a 2013 U.S. Justice Department survey of 240 prisons and 358 jails across the country found that the Colorado women’s prison had the highest rate of alleged sexual assault or sexual misconduct by staffers.

Nearly 11 percent of inmates at Denver Women’s Correctional Facility claimed they were victim of sexual abuse by correctional staffers, the study showed. That rate was four times the national average, it says. The lawsuit mentioned the study.

Raemisch, the warden and other CDOC supervisors failed to stop the persistent abuse, the lawsuit says.

“In light of the post-2009 history of widespread and persistent sexual abuse by staff against inmates, the need for additional and effective training, supervision and discipline of guards regarding sexual acts with inmates was obvious,” the lawsuit says.