Police Superintendent Warren Riley promised Thursday to investigate the latest accusations of brutality against members of his beleaguered department — accusations made by a fellow officer's wife.

"This is not something that's going to fade away," Riley told a news conference.

Investigators have already interviewed more than a dozen people and are getting conflicting accounts of what happened Tuesday to Jonie Pratt, who suffered a swollen forehead, a black eye and a fractured wrist.

Her mother-in-law, Dulcie Scott, says she saw Pratt being beaten after a traffic stop.

"It was terrifying," said Scott, who said she tried to stop the brutality by telling officers that Pratt's husband, Desmond, is a 10-year veteran of the police department. Pratt's sister, Nancy Parker, has been a member of the force for three years.

Scott said all three officers were white; Pratt is black. On Thursday, Riley said one of the accused officers is black.

He identified the officers as Jason Giroir, a six-year department veteran, and Ryan Vaught and Joseph Haines, each with about 1 1/2 years on the force. Haines is black, Riley said.

The probe comes less than a week after two former officers — both white — were indicted in the French Quarter beating of a black retired teacher, violence caught by an Associated Press news crew covering the storm's aftermath in October.

The local NAACP is calling for a federal investigation. "We have a problem with this kind of thing that went back before Katrina," said Danatus King, president of the New Orleans chapter of the NAACP.

The FBI said it is conducting a preliminary inquiry to determine whether the case warrants further investigation.

Pratt was charged with flight from an officer, battery, resisting arrest, running a stop sign and making an illegal turn.

The Pratts refused to discuss the matter, but Scott said Pratt was returning from visiting her sick father in Baton Rouge early Tuesday when police said she ran a stop sign about two blocks from her house. The woman drove to her house in a middle-class area of the city before pulling over.

"I saw an officer pull Jonie out of the car by her hair," said Scott, who was babysitting her grandchildren at the couple's house. "He was swearing at her and pounding her into the car. I said, `Stop that, that's Officer Pratt's wife."'

Scott said the officer twisted Pratt's arms behind her and sprayed Mace in her face. She said two more white officers arrived and the three shoved the 5-foot-2 Pratt to the ground and knelt on her back, and an officer kicked her in the head.

The white officers refused to believe that Pratt, a school teacher on leave since Katrina, lived in the house she claimed was hers, Scott said.

"It's a nice area and I think they meant a black family wouldn't live there," Scott said.

Pratt was released from the handcuffs after several black officers showed up, Scott said. "It turned into this real black-white situation between the police," Scott said. "All the white officers on one side, the black officers on the other."

In Katrina's aftermath, New Orleans police officers were accused of abandoning their posts, stealing cars and looting stores.