Cop Went Rogue In Burlington Coat Factory Shooting, Use of Force Expert Says

The LAPD officer who fired the fatal rounds in the Burlington Coat Factory shooting, killing the suspect and an innocent bystander, looked like he went rogue ... so says a retired cop.

Timothy Williams Jr., an expert on the use of force in policing and a retired LAPD detective supervisor, joined us Tuesday on "TMZ Live" and he broke down the police body cam footage in the fatal shooting ... and it's his opinion the shots were not justified.

The first thing that jumped out to Timothy ... the cop with the AR-15 appearing to act separately from the rest of the cops and gun down the suspect, even though other police in the group had less-lethal weapons.

Remember ... the suspect was wielding a bike lock and chain, bloodying a shopper and injuring others before cops arrived ... and Timothy says the use of force was warranted in this situation, but he thinks police didn't need to use lethal force and fire an assault rifle.

As you know ... the bullets from the AR-15 killed the suspect, as well as a 14-year-old girl who was cowering in the background in a dressing room. The walls in these kinds of stores are usually paper-thin, and the L.A. County Medical Examiner says a bullet struck her in the chest and killed her.