Rule 1 with talking to police in a car is always keep both hands on the stearing wheel at all times or keep you hands whare the officer can see them if in passenger or back seat rule 2 is always comply with the officer even if you are in the right and he is wrong take your Battle to the court Room the odds are better and you don’t end up like Swiss cheese cause you reached for some chewing gum and the cop mistakes it for a loaded fire arm

Plainclothes Chicago police officers fired nearly 100 gunshots over 41 seconds during a traffic stop that left one man dead and one officer injured

Five officers from a tactical unit who were in an unmarked police vehicle surrounded an SUV last month driven by Dexter Reed, allegedly for failing to wear a seatbelt.

https://abc7chicago.com/dexter-reed-chicago-police-shooting-body-camera-video-copa/14637195/

From the video: The 26 year old was already facing illegal gun charges and if the cops found the gun he'd be going back to jail.

Plainclothes Chicago police officers

At least one clearly had a vest on marked POLICE

It's very likely they ran the plates, knew he was up on weapons charges, saw him not wearing a seatbelt and used that as a pretence to pull him over. End of the day he was a criminal doing criminal things who shot a cop first.