The report, issued Friday, found one police officer fired four rounds at McDade from a distance of less than 1 foot, saying McDade had reached for his waistband. A second officer responding on foot fired four rounds -- and said he thought his partner may have been exchanging gunfire with a suspect, the Los Angeles Times reported.
Police had been responding to a report of an armed robbery -- but a subsequent investigation determined McDade had not been armed, and the man who called police had said the suspect was armed because he thought that might prompt a faster response.
The report said McDade, who was 19 when he was killed, was handcuffed after he was shot, with police saying he had been "combative." Paramedics were called to the scene, and McDade died at a hospital about 90 minutes after the shooting.
The FBI said in April it planned to investigate whether the killing involved civil rights violations.
McDade's parents, Anya Slaughter and Kenneth McDade, have filed a federal lawsuit alleging McDade was shot multiple times in the chest but did not die immediately, the Times reported. The suit alleges McDade tried to speak with a police officer but was left on the street for a long period without medical attention.