According to the reports, a fourth ex-New Orleans police officer and a man who pretended to be a deputy pleaded guilty Wednesday in the Danziger Bridge shootings after Hurricane Katrina.

Former officer Robert Barrios pleaded guilty in U. S. District Court to conspiring with fellow officers to obstruct justice by covering up the fatal shootings by police on the bridge in the days after Hurricane Katrina in 2005, the U. S. Justice Department said in a release.

The (New Orleans) Times-Picayune reported that meanwhile, Marion Ryder, 45, of Opelousas, La., admitted in federal court he lied about the victims being armed and shooting at police. Ryder also admitted being a felon illegally in possession of a firearm, carrying a handgun during the hurricane.

Ryder was a key witness in the original investigation of the Sept. 4, 2005, police shooting on the bridge that left two civilians dead and four civilians injured. He was the first non-police officer to plead guilty in the case.

It was also reported that three other former New Orleans police officers pleaded guilty previously -- former Lt. Michael Lohman, former Detective Jeffrey Lehrmann and former Officer Michael Hunter.

U. S. Attorney Jim Letten said, "Today's conviction of the fourth New Orleans police officer on federal felony charges arising out of the cover-up of the true events surrounding the unprovoked shooting of innocent citizens on the Danziger Bridge, as well as the earlier guilty plea by a civilian, evidence our commitment to relentlessly pursue justice and hold accountable all of those responsible for the injustices to which the victims were subjected. As we begin to enter the second, critical phase of this case, we will do whatever it takes to achieve true justice in the vindication of the precious rights of all citizens."

There is evidence a fifth officer was involved, FBI Special Agent in Charge David Welker said. (With Inputs from Agencies)