Updated

Federal officials will investigate the New Orleans police officers involved in fatal shootings that happened on a city bridge after Hurricane Katrina, authorities said Tuesday.

The announcement comes two weeks after the dismissal of charges against seven New Orleans police officers accused of gunning down several people on the Danziger Bridge in the chaotic aftermath of Hurricane Katrina, killing two men.

"In the best spirit of law enforcement coordination, and at the request of the victim's families, the New Orleans District Attorney has referred the matter to the United States Department of Justice for review," U.S. Attorney Jim Letten said in a statement.

Letten said his office, the Civil Rights Division of the Justice Department and the FBI would take "as much time and resources as necessary" to determine if the officers will face federal criminal charges.

Police officials have acknowledged the officers shot people from both sides of the bridge, but said they were shot at first.

State District Judge Raymond Bigelow threw out first-degree murder and attempted murder charges against Sgt. Kenneth Bowen, Sgt. Robert Gisevius Jr., Officer Anthony Villavaso II and former Officer Robert Faulcon Jr. Bigelow also threw out attempted first-degree murder charges against Officer Mike Hunter Jr. and Officer Robert Barrios and attempted second-degree murder charges against Officer Ignatius Hills.

Faulcon resigned from the police force; the other officers were assigned to desk duty after their indictment in December 2006.

"I am totally shocked," said attorney Franz Zibilich, who represents Faulcon.

"You would think if the Feds were interested they would have investigated long before this."

In throwing out the charges, Bigelow agreed with defense arguments that prosecutors violated state law by divulging secret grand jury testimony to a police officer who was a witness in the case.

"The violation is clear," Bigelow said in court as he announced the ruling.

Katrina struck on Aug. 29, 2005. In its aftermath, levees broke, flooding 80 percent of New Orleans. Chaos gripped the city, and looting was reported in some areas. Rescuers said they thought gunfire was directed at them.

Later investigation revealed at least some of the shooting was by residents trapped by floodwater trying to attract the attention of rescue parties.

Survivors of the Sept. 4, 2005, shootings have said the officers fired at unarmed people crossing the Danziger Bridge to get food at a grocery store. Ronald Madison, a 40-year-old mentally disabled man, and James Brissette, 19, were shot and killed by police. Four other people were wounded.

The officers acknowledged shooting at people on the bridge, but said they did so only after taking fire.

After Bigelow quashed the indictments, religious and civil rights groups in New Orleans called for the district attorney to refile charges against the officers.

The family of one of the men shot had also asked for the Justice Department investigation.

Then interim district attorney Keva Landrum-Johnson also asked U.S. Attorney General Michael B. Mukasey to have his civil rights division investigate the case, according to a letter dated Aug. 8 that the family provided to reporters.

"We're very happy, said Dr. Romell Madison, older brother of Ronald Madison. "I think we have a better playing field now, with a chance of justice being reached more quickly now that we will be without the politics of the local system."

The officers still with the police department were removed from contact with the public and wore tracking devices following their indictments. After Bigelow quashed the charges, the court ordered that the tracking devices be removed. All have since returned to regular duties, said police spokesman Bob Young. Police superintendent Warren Riley is evaluating the situation, Young said.

"The superintendent is reviewing his options and will decide whether to leave them on regular duties or put them back in some kind of non-contact role," Young said.

The New Orleans District Attorney's office withdrew its right to appeal the dismissal of state charges on Tuesday, said spokeswoman Nayita Wilson. She refused further comment.