New Orleans prosecutors will not pursue charges against a police officer who shot and killed a man at a New Orleans East apartment complex during a sting operation targeting another man.

Prosecutors decided, without taking the case to a grand jury, that there was not enough evidence to charge Officer Terrance Hilliard with any crimes in connection with the Jan. 24 death of Arties Manning III, a spokesman for District Attorney Leon Cannizzaro confirmed Thursday.

The office disclosed its decision to the Police Department and Manning’s family in September. It has not been previously reported.

Manning’s mother expressed dismay at the decision and promised to keep fighting in her son’s name. She said she is still trying to obtain a full police report on the investigation into her son’s death.

“Justice for my son has not been served, and his mother is not giving up,” Natasha Manning said.

A spokesman for the Fraternal Order of Police praised prosecutors' call.

"While police officers dread having to use deadly force, sometimes officers are faced with circumstances where whether they get home to their family is in doubt," Donovan Livaccari said. "The district attorney made the right decision based on a thorough investigation by the Force Investigation Team."

Hilliard, a seven-year NOPD veteran, was wearing street clothes as part of an operation to arrest another man in connection with a string of armed robberies when he and other officers went to the Carriage House apartment complex, 10151 Curran Blvd.

Manning had nothing to do with the armed robberies, police later said. But when officers tried to stop him in a courtyard of the apartment complex, he ran, according to the department’s account. Police said that Manning was holding a gun and turned toward Hilliard before the officer opened fire, striking Manning three times and killing him.

The 26-year-old was shot in the shoulder, side and back, “perforating multiple organs, including the lung, spleen and liver,” according to the Coroner's Office.

Police later released footage from another officer’s body-worn camera that they said showed Manning holding a gun, although an attorney for his family disputed that interpretation of the grainy video.

The Police Department's Public Integrity Bureau concluded that Hilliard should be cleared of any crimes on Aug. 16 and turned the case over to the district attorney.

About five weeks later, prosecutors came to the same conclusion. In a Sept. 21 letter to Police Superintendent Michael Harrison, First Assistant District Attorney Graymond Martin said prosecutors would not pursue charges.

"After a thorough review of the investigation conducted by the Public Integrity Bureau's Force Investigation Team, the DA's Office has determined that the evidence does not form a sufficient basis for the institution of a prosecution,” Martin said.

The decision is not likely to put to rest the controversy around the case, much of which has centered on the fact that Manning was not a suspect in the armed robberies that sent police to the complex in the first place.

A search warrant obtained by The New Orleans Advocate does outline a potential explanation for why Manning might have run from police.

The warrant states that a gun found near Manning’s body had been reported stolen from the parking garage at the Canal Street hotel where he worked.

“A weapon was found in a holster near the deceased person. That weapon was found to be stolen from a vehicle at a hotel in the French Quarter on Friday, Dec. 30, 2016, after the vehicle had been given by the owner to a valet to be parked,” the warrant states.

Manning’s mother has said from the start that she did not know her son to own a gun. She said her son was working as a manager at the parking garage, not a valet with access to cars.

“What does that have to do with the officer shooting my son in the back while he was running away?” she said.

Detective Michael McCleery’s warrant also reveals another new detail about the internal investigation into Manning’s death. It says that one person in the apartment complex claimed to have seen an officer remove a weapon from Manning’s waistband and place it on the ground.

If true, that assertion could suggest that a police officer tampered with the scene to make it appear that Manning had drawn his gun.

However, McCleery wrote in his warrant that “the officer the person described as removing the weapon was an officer with a body-worn camera, the footage from which showed he never approached the deceased person.”

The warrant sworn by McCleery sought permission to perform a DNA test on Hilliard, the officer. It’s not clear whether DNA testing suggested that Hilliard touched Manning’s gun. Police later claimed that another officer's body camera video showed Manning holding a weapon.

Natasha Manning and her attorney, Katie Schwartzmann from the MacArthur Justice Center of New Orleans, said they are still searching for answers about why Manning died. They said the Police Department and the DA’s Office have not released crucial police reports in the case.

“Neither the DA nor PIB has released the files to the family despite our requests having been pending for months,” Schwartzmann said. “If they don’t turn them over soon, we’re going to have to file suit. It’s outrageous to provide information to the media yet not provide the full file to the affected family.”

Follow Matt Sledge on Twitter, @mgsledge. | (504) 636-7432