By Ian Simpson

(Reuters) - Minnesota prosecutors who will decide on charges in the fatal police shooting of a black motorist will include a special prosecutor to guarantee independence in the case, a county attorney said on Friday.

Ramsey County Attorney John Choi said Minneapolis defense lawyer Don Lewis would join his team to help weigh possible charges arising from the death of Philando Castile this month.

Lewis, a former federal prosecutor and law school dean, will "provide an independent perspective bolstered by the authority of this office," Choi said at a news conference.

The appointment of Lewis, who is black, came after the lawyer for Castile's family and the American Civil Liberties union had asked Minnesota's governor and attorney general to name a special prosecutor to handle the high-profile case, Choi said.

Castile, 32, was shot on July 6 in Falcon Heights, a St. Paul suburb, during a traffic stop. The shooting, along with that of a black man by police in Baton Rouge, Louisiana, a day earlier, inflamed debate in the United States over police treatment of minorities.

Protests were intensified by a video of the bloody aftermath that Castile's girlfriend Diamond Reynolds had streamed live on the internet from the car.

Reynolds said in the video that officers told them Castile was stopped for a broken tail light, and was getting his license and registration when he was shot. Authorities have not confirmed the reason for the stop.

An attorney for the officer who shot Castile, Jeronimo Yanez of the St. Anthony Police Department, has said he was reacting to the presence of a gun and not Castile's race.

Choi said prosecutors had to wait for the results of the investigation by the state's Bureau of Criminal Apprehension before beginning to decide whether to bring charges or send the case to a grand jury.

Castile's shooting came the day before an African-American gunman killed five police officers during a protest march in Dallas. In a separate racially charged rampage, a black ex-Marine shot two police officers and a sheriff's deputy in Baton Rouge on July 17.

(Editing by Bernadette Baum)