The St. Paul Police Department placed an investigator on leave Thursday, a day after a federal appeals court said she was not truthful in a major sex trafficking case that allegedly stretched from the Twin Cities to Nashville, Tenn.

The appeals court blasted the government for its handling of the case involving Somali gang members and said the alleged victims in the case had serious credibility issues.

A federal judge had opined that Sgt. Heather Weyker “likely exaggerated or fabricated important aspects” of an alleged victim’s story, the appeals court said. Weyker, a longtime officer who was the lead investigator on the high-profile case, was also caught lying to a grand jury and later during a detention hearing, for which the court “scolded her,” according to the 6th U.S. Circuit Court of Appeals decision filed Wednesday.

The court’s findings bring Weyker’s past cases into question, as well as her future as an officer.

St. Paul police spokesman Steve Linders said Thursday that the information in the court documents “is extremely concerning, which is why we have launched an investigation.”

“We are going to take a hard look at the information in the court documents, gather more information and take appropriate steps to ensure the integrity of all future investigations,” Linders said.

Nashville-based defense attorney Jennifer Thompson, who represented defendant Idris Fahra, said there were inconsistencies in the story of the girl at the center of the case. She wondered why Weyker and prosecutors pushed ahead anyway.

“The problem is, and I do see police officers exaggerating a lot, they get caught up in really needing to get a conviction,” Thompson said. “Police officers can be really righteous and they really believe they know who are the good people and who are the bad people. And many times police officers get a story in their head about how they want a story to be, and then they get this factual bias … and all the things that don’t fit with their theory, they disregard.”

Weyker’s truthfulness in the case came up in 2012, according to court documents, but Linders said it had not been brought to the police department’s attention. The police department began an internal investigation Thursday upon learning of Wednesday’s appeals court finding.

The Ramsey County public defender’s office said it will likely look into past cases involving its clients and Weyker, while local prosecutors’ offices said they are considering their next steps. Ramsey County Attorney John Choi has asked his staff to review the appeals court decision and “determine the proper course of action as it relates to any review of current or past cases,” said his spokesman, Dennis Gerhardstein.

If a police officer has been found to be dishonest in the past, prosecutors are required to turn over that information to defense attorneys in future cases. And the defense could use that evidence to question the officer’s testimony in their case.

“It’s pretty obvious that (Weyker’s) future as an investigator is ruined, assuming the St. Paul Police Department follows typical disciplinary procedures,” said Candace McCoy, a criminal justice professor at the John Jay College of Criminal Justice in New York, in an email Thursday. “In fact, if she lied under oath, she should be fired.”

Weyker could not be reached Thursday. An attorney for the St. Paul police union said he didn’t have enough information to comment because he had not had an opportunity to review the case.

On Wednesday, the federal appeals court said a U.S. district judge had good reason when he threw out guilty verdicts involving three men who were convicted by a jury in 2012 of sex-trafficking conspiracy. The three men were part of a case involving 30 people who were all accused of being part of a multistate child sex trafficking operation that took place in Minnesota, Ohio and Tennessee. The appeals court said the claims of sex trafficking “may be fictitious.”

When the federal charges were filed in 2010, Weyker and her supervisor said they had spent thousands of hours on the case. Weyker, who was assigned to a human trafficking task force, had started the investigation in 2008, after police said a family had contacted them and asked for help.

Weyker had gone in 2008 to the Minneapolis-area home of a Somali refugee family to speak with their ninth-grade daughter, referred to as Jane Doe 2 in court documents, but her parents objected so Weyker met her “surreptitiously at her school,” according to the appeals court ruling filed Wednesday. Jane Doe 2 was “an Americanized teenager … living in an ultra-conservative, African, Muslim household” and “a habitual runaway,” the court said in its finding.

Weyker recorded her meetings with the teen, the opinion said, and they “produced a story in which Jane Doe 2 was not a troubled runaway or a juvenile delinquent, but was instead an innocent child taken in by a Somali gang who used her for sex, either as a prostitute or for free with gang members.”

Thompson, Fahra’s attorney, said there were red flags along the way, and she reported them to the court. For example, she said the defense learned just before trial that Weyker had an audio recording of an interview with Jane Doe 2, but that recording had not been turned over. After receiving the recording, Thompson listened to it and compared it to the investigator’s notes from the interview and noticed “so many things (Weyker) misstated, or exaggerated.”

Weyker “also lied on an application to get Jane Doe 2’s family some $3,000 from the Tennessee victim’s compensation fund,” by claiming the young woman had been abducted, though “Jane Doe 2 flatly denied an abduction,” the appeals court wrote.

David Boling, a spokesman for the U.S. attorney’s office in Nashville, said Thursday: “We are reviewing the decision of the Sixth Circuit and assessing how it may impact the government’s case against each of the remaining 16 defendants.”

Thompson’s client — along with other defendants who were acquitted in the case — was arrested six years ago and ended up spending two years in prison for crimes he didn’t commit, she said.

“It took four judges to review this stuff and say this did not happen,” Thompson said. “And the judges aren’t even the ones who investigated. How is that an investigative team and four judges reviewed this and it appeared to them it didn’t happen, yet it didn’t occur to a police officer? How did she not see that? How did the prosecutor not see that?”

When the federal charges were filed in 2010, they drew widespread attention. St. Paul police spoke then about the time and effort it took law enforcement to get victims to trust them in any trafficking case. Weyker said she did so by “being a constant in their life.” She would give her cellphone number to victims, whom she called “my girls,” and they would sometimes call her in the middle of the night just to talk, Weyker said in 2010.

Weyker started her career as a cop in Los Angeles, where she worked for three years. She has been a St. Paul police officer since 1997. She investigated vice or human trafficking cases between 2007 and 2012, and has been an investigator in the police department’s juvenile unit since last April.

The police department put Weyker on paid administrative leave Thursday. Linders said he could not disclose the reason why.

Weyker was the subject of 12 previous complaints at the St. Paul Police Department, five of which resulted in discipline. Four were oral reprimands and she received a written reprimand in October for not notifying a supervisor when an off-duty officer was found to have crashed his car after drinking and driving.

Weyker has received 15 commendations, including a medal of commendation in 2002 for her work the year before in a three-month undercover drug operation.

The Associated Press contributed to this report.