(CBS DETROIT) – Attorneys Ben Crump and Ven Johnson, representing the family of Patrick Lyoya, say the 26-year-old’s death was an unnecessary killing of an unarmed Black man. They say they have scientific evidence to prove Lyoya was shot execution style in the back of the head.

Driving while Black is what Crump says made Lyoya a target by Grand Rapids police.

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Crump made the announcement during a press conference Tuesday in Downtown Detroit.

“He profiled this black motorist and turned his car around because when he turns his car around what you see is Patrick’s car is about a block and a half away from him and then all of a sudden you see the lights on,” he said.

Forensic Pathologist Dr. Werner Spitz conducted an independent autopsy Saturday and says there’s no doubt Lyoya died from a gunshot wound to the back of the head.

“He knew he was fully aware at one point or over a period depending on what transpired before that there’s a gun being held to his head,” Spitz said.

The legal duo also made claims that the officer, whose name is concealed, never gave verbal warnings before pulling the trigger.

“Which is required under the federal law, if it’s feasible is the word,” Johnson said.

“Never gave a warning, halt or I’m going to shoot you or other words that we can all imagine.”

Lyoya was pulled over April 4 for having a license plate that didn’t match the car.

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Crump says the officer escalated a misdemeanor traffic stop into a deadly execution.

“How did he know that Patrick’s tag registration wasn’t valid when he’s coming from the opposite direction?” Crump questioned.

Lyoya’s family is seeking charges in the case and demanding for the officer to be fired.

Crump and Johnson also stated Lyoya was not fighting with the officer but resisting.

“If they’re going to try and run with that he can shoot somebody because you can actually zap somebody, under the law, that would be deadly force for a non-deadly force situation, can not happen,” Johnson said.

Video footage of the incident appears to show the two struggling over the officer’s taser moments before the fatal shot.

Michigan State Police are conducting an investigation.

The Kent County prosecutor is expected to review the case once MSP concludes.

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