District Attorney Herbert "Buzz" Franklin speaks to Assistant District Attorney Chris Arnt while he is on the stand appearing before Cobb County Superior Court Senior Judge Grant Brantley during a pre-trial hearing to determine if FBI agent Ken Hillman is guilty of impropriety while at the Catoosa County Courthouse on Monday, April 19, 2015.

A federal investigator in North Georgia admitted to letting an untrained woman serve as an undercover officer, jeopardizing an operation to stop child molesters.

Ken Hillman, a former FBI special agent who ran a "To Catch a Predator"-style task force in Rossville pleaded guilty to sharing confidential information in U.S. Magistrate Court on Thursday. One member of the task force told his boss that Hillman was sleeping with the woman he brought into the team, Angela Russell.

Hillman's bosses did not give him clearance to let Russell serve as an officer, according to a news release from the U.S. Department of Justice. He also let her husband, Emerson Russell, watch members of the task force chat with targets and ride along for "sting" arrests.

Hillman's charge carries a punishment of up to 1 year in prison or a fine of up to $100,000. A U.S. District Court judge is scheduled to sentence him Sept. 22.

The task force disbanded in 2013, but cases against three people arrested by Hillman's team are still pending in Catoosa County Superior Court, said defense attorney McCracken Poston. A judge overseeing those cases has continually delayed trials because of the investigation against Hillman.

On Friday, Lookout Mountain Judicial Circuit District Attorney Herbert "Buzz" Franklin said he still plans to prosecute the cases. Poston said he will subpoena Hillman's personnel file, as well as the evidence the Department of Justice compiled against Hillman.

Cindi Yeager, a defense attorney for another suspect with pending charges, said she expects Franklin to hand over all the evidence as discovery material.

"That's what Mr. Poston and I have been waiting for all these years: For the truth to finally come out," she said.

With Hillman in charge, the task force began in 2006 and consisted of officers from Rossville police, Ringgold police and the Catoosa County Sheriff's Office. They would post on websites like Craigslist, pretending to be stepfathers and uncles offering their children to strangers.

When people contacted them and said they wanted to have sex with the children, an undercover officer would tell them where to meet. When the suspect arrived, investigators were waiting.

In 2012, a member of the task force reached out to Emerson Russell, a local businessman who develops properties and owns a janitorial, maintenance, security and landscaping company. He is active in the community and has particularly strong relationships with police officers.

He said the task force member told him they needed a place to operate. They couldn't chat with targets from computers at a police station. A tech-savvy suspect might be able to trace their location, killing the case. Emerson Russell offered them a duplex next to his own home off Mack Smith Road.

Soon after, he met Hillman. So did his wife. Hillman let the Russells watch officers chat with their targets, according to the Department of Justice. Then, he let them ride along with the officers when they confronted a suspect. Emerson Russell said he also watched his wife chat online with some of the task force's targets.

He became suspicious of his wife's relationship with Hillman, which came to a head in October 2012. According to a Ringgold police internal investigation, Hillman met with Angela Russell at a bar one night. When the two were leaving, a bartender called the police to report a potential drunk driver.

Sgt. Tom Evans found them in the parking lot, according to the investigation, and drove them to a condo in East Brainerd. Emerson Russell later found Hillman and his wife there. He filed for divorce three months later, citing adultery.

In February 2013, Emerson Russell told Poston about his wife's involvement in the task force. Poston, in turn, met with an FBI agent he knew at a restaurant in Calhoun. The agent reported the allegations to his boss, triggering a criminal investigation and Hillman's suspension. He eventually retired for a medical condition, according to the Department of Justice.

Poston believes prosecutors could have been harsher toward Hillman, arguing he did not disclose Angela Russell's involvement in the investigations when meeting with grand juries. Also, a former police chief said his officer told him he once let Hillman go after he appeared to be driving drunk in Catoosa County.

"He was an FBI agent who probably did some good work," Poston said. "But his last few years were problematic on a couple of fronts."

Said Emerson Russell: "If you or I had [driven drunk], we wouldn't have gotten that same treatment. That's what I think: It should be fair for everybody. But the system, they got it worked out. We just got to move on."

Poston expects to cross examine Angela Russell during his client's criminal trial. At a hearing in May 2015, she took the stand but pleaded the Fifth Amendment for about 30 minutes. Her attorney, Steve Sadow, said Friday that he will advise her to do what's in her best interest if she has to return to court.

Dave Scroggins, a Rossville detective who served on the task force for seven years, said the criminal allegations against Hillman clouded an otherwise honorable operation. He said they arrested 158 child predators and saved 14 girls who were "actively being molested."

In one of their first cases, he said, he found his target in a Chattanooga hotel room. The man was with a teenage girl he had kidnapped from Ohio. They were lying on the bed naked, watching porn, when officers arrested him.

"Everybody forgets the good stuff this task force did," he said. " It's a shame to let really, really good police work just go by the wayside."

Contact Staff Writer Tyler Jett at 423-757-6476 or Follow him on Twitter @LetsJett.