NEW ORLEANS – Four more New Orleans police officers have been charged in the deadly shootings of two people in Hurricane Katrina’s chaotic aftermath and could face the most serious punishment yet — the death penalty — in the killings, which have brought down a string of other officers.

Six current or former officers are charged in a 27-count indictment unsealed Tuesday. Five former New Orleans police officers already have pleaded guilty to helping cover up the shootings on the Danziger Bridge that left two men dead and four wounded just days after the August 2005 hurricane. In one instance, a mentally disabled man was shot in the back and stomped before he died.

The indictment charges Sgts. Robert Gisevius and Kenneth Bowen, officer Anthony Villavaso and former officer Robert Faulcon with deprivation of rights under color of law and use of a weapon during the commission of a crime.

They could face the death penalty if convicted, though U.S. Attorney Jim Letten said prosecutors haven’t decided whether to seek that punishment.

Sgt. Arthur Kaufman and retired Sgt. Gerard Dugue, who helped investigate the shootings, were charged with participating in a cover-up to make it appear the shootings were justified. Charges against them include obstruction of justice.

The five former officers who already have pleaded guilty in the Danziger case are cooperating with prosecutors while they await sentencing. They pleaded guilty to lesser charges than those in this week’s indictment.

The case is one of several probes of alleged misconduct by New Orleans police officers that the Justice Department opened after the storm. Last month, five current or former officers were charged in the shooting death of Henry Glover, 31, whose burned body turned up after Katrina.

Attorney General Eric Holder said the Justice Department is working with city officials to restore residents’ trust in the police department.

“Put simply, we will not tolerate wrongdoing by those who are sworn to protect the public,” Attorney General Eric Holder said Tuesday in New Orleans.

Eric Hessler, a lawyer for Gisevius, said the indictment wasn’t a surprise.

“We have long anticipated that this day may come,” he said. “We’re certainly ready to begin the process of defending him against these allegations.”

Claude Kelly, a lawyer for Dugue, called the indictment “a travesty” and denied his client participated in a cover-up.

Faulcon, who resigned from the department shortly after the storm, was arrested at his home in Houston on Tuesday. Gisevius, Bowen and Villavaso surrendered at FBI headquarters in New Orleans.