Hetznecker said the shooting appeared to be part of a "pattern of police shootings over the last few years."
"Our society invests a tremendous amount of power in the Police Department to enforce the law, and rightfully so," Hetznecker said. "But that power must coincide with an unwavering respect for the civil rights of citizens. This particular case is an extreme use of excessive force, unwarranted under any scenario."
Christine O'Brien, a Philadelphia Police Department public affairs officer, said officials could not comment on pending litigation.
Named as defendants were narcotics Officers John McCarron and Mark Oliveras and 35th District Officers Joseph Burke, George Fox, Craig Coulter, and Brandon Bryant.
At the time of the shooting, police officials described it as justified after a high-speed chase through North Philadelphia that ended only when the stolen car rammed police cars blocking its way.
Police said that the car's two occupants had long criminal histories and refused to get out of the car and that one appeared to be reaching under his seat. Officers around the car opened fire, killing Moses, who was in the front passenger seat, and critically wounding driver Frederick Bell.
Hetznecker said his investigation raised doubts about the circumstances leading to the shooting.
He said vehicle damage made it more likely that the police cars struck the stolen car, a Chevrolet Impala sedan, than that the car rammed the cruisers.
"This was not a high-speed chase, this was a slow-speed chase," added J. Whyatt Mondesire, president of the local NAACP chapter, who joined Hetznecker and Carolyn Moses to announce the suit.
No gun was found in the stolen car or on the two men, Hetznecker said.
Mondesire said investigators recovered 62 fired cartridge casings from the scene; Bell was struck 12 times but lived.
