Updated

Prosecutors intend to retry a retired police sergeant charged with helping cover up deadly shootings on a New Orleans bridge after Hurricane Katrina.

U.S. Attorney Jim Letten made the announcement late Friday but declined to provide further comment.

Earlier Friday, U.S. District Judge Kurt Engelhardt declared a mistrial in the case of Gerard Dugue, ruling that Justice Department prosecutor Bobbi Bernstein may have tainted the jury hearing the trial by mentioning the name of a man who was beaten to death by a New Orleans police officer in a case unrelated to Dugue's.

Dugue was on trial for charges he wrote a false report on the shootings of unarmed residents on the Danziger Bridge, less than a week after the August 2005 hurricane. The case was expected to go to the jury early next week, the last of 20 New Orleans police officers who were charged by the Justice Department's civil rights division to get his day in court.

Engelhardt ruled that Justice Department prosecutor Bobbi Bernstein may have unfairly influenced the jury hearing Dugue's trial by mentioning the name of a man who was beaten to death by a New Orleans police officer in a case unrelated to Dugue's.

Bernstein argued that merely mentioning Raymond Robair's last name couldn't amount to any prejudice against Dugue. The retired sergeant wasn't charged in the Robair case, but the judge said it's impossible to know if any jurors heard her remark and drew any negative conclusions.

"That's a chance that I'm not willing to take," he said, adding that a mistrial was "the last thing in the world I want to do."

The hurricane, which struck Louisiana and Mississippi on Aug. 29, 2005, drove a wall of water into the coast. Levees broke and flooded roughly 80 percent of New Orleans, plunging the city into chaos and subjecting police to harsh, dangerous conditions.

The storm also cast a spotlight on a troubled police department that has been plagued by corruption for decades. In Katrina's aftermath, federal authorities launched a new push to clean up the police force. The criminal probes were only part of the effort. The Justice Department also embarked on a top-to-bottom review of the department that produced a scathing report on its practices.

Before the trial started, Engelhardt barred prosecutors from introducing evidence related to Dugue's involvement in the department's probe of Robair's death. Defense attorney Claude Kelly asked for a mistrial after he heard Bernstein turn to a colleague and say, "Get me Robair," while cross-examining Dugue. Bernstein was asking for a file related to the Robair case.

Bernstein said she wanted to ask Dugue about his report in the Robair case to show he knows how to properly write a report and is capable of assessing whether witnesses are credible or not.

Kelly, however, said Bernstein's "outrageous behavior" could have left jurors with the impression that Dugue was suspected of wrongdoing in the Robair case. Engelhardt angrily scolded Bernstein, saying she should have privately discussed the matter with him at the bench if she thought she could broach the subject.

"My orders are my orders, and I expect them to be followed," he said.

Earlier Friday, on the fifth day of his trial, Dugue denied participating in a cover-up, claiming he didn't learn until years later that police shot innocent, unarmed people on the bridge.

Dugue said he now knows some of his former colleagues lied to him about their actions on the bridge less than a week after the 2005 storm. He said he didn't learn the truth — that police shot six people, killing two, without justification — until after other officers started cooperating with a federal probe of the shootings and pleaded guilty in 2010 to participating in a cover-up.

"If anybody says anything about me being involved in a cover-up, they're a liar," he said.

Prosecutors said Dugue rigged his investigation of the Sept. 4, 2005, shootings and submitted a false report to clear several officers who opened fire on the bridge as they responded to another officer's distress call.

During her cross-examination of Dugue, Bernstein pressed him to explain why he didn't do more to verify or challenge the officers' accounts of the shootings.

"Your job is not to just type out what people say and be done," Bernstein said.

Dugue said he didn't have the "supporting cast" to conduct a more thorough investigation because the police department was overwhelmed in Katrina's chaotic aftermath.

"I didn't have the tools, the resources, the people to do that teamwork," Dugue said. "It wasn't there."

He wasn't charged in the shootings and didn't get involved in the case until six weeks later, when he was assigned to take over the department's investigation. Prosecutors said the cover-up, which included a planted gun, phony witnesses and falsified reports, already was in motion when Dugue inherited the investigation from Sgt. Arthur Kaufman in October 2005.

Dugue said his "jaw dropped" when he learned Kaufman hadn't collected any shell casings or other physical evidence from the scene of the shootings. Dugue said he immediately dispatched a crime scene technician to comb over the bridge. Still, Dugue insisted he didn't have any reason to suspect that Kaufman or the shooters were lying.

"I did not know anything about any kind of cover-up," he said.

Kaufman is one of five current or former officers convicted in August of civil rights violations stemming from the shootings. They are scheduled to be sentenced April 3.