By Cherri Gregg

PHILADELPHIA (CBS) — The mother of Brandon Tate-Brown, the man killed by police during a traffic stop in Frankford last December — sued the city of Philadelphia and two police officers involved in the shooting on Tuesday. The state class action lawsuit seeks damages for wrongful death, assault and demands police reforms.

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“I believe that my son’s rights were violated,” says Tanya Brown-Dickerson, “I want honesty and transparency and accountability, and I want new laws.”

Police reports say Brandon Tate-Brown was shot in the back of the head by police. According to officer accounts, Tate-Brown was reaching for a gun when he was shot and they located a stolen firearm in his vehicle. Internal Affairs cleared the two officers involved and the district attorney launched a three-month investigation that resulted in no charges being filed. But the Brown family claims the facts don’t add up.

“We dispute the official police account of this shooting,” says Brian Mildenberg, an attorney who represents Brown-Dickerson. He says police showed him and Brown-Dickerson video that disputes their own account of what happened that night.

“We have a big problem with the police officers and the police department in this case and part of our goal is to bring this evidence to the public,” he says.

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The complaint sites recent Department of Justice findings and recommendations as evidence there’s systematic problems within the department, such as lack of training, deficient deescalation polices and inconsistent investigation procedures. They claim these problems left room for error and possibly a cover up.

“The credibility of the police department in this case is zero,” says Mildenberg.

The suit seeks damages, but the family says it’s about more than just money.

“I want honesty and transparency and revised and new laws,” says Brown-Dickerson, “That’s what I want.”

Mark McDonald, city spokesman, responded to a request for comment with the following statement:

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“We don’t comment on pending litigation. We will respond to it through court filings in the normal course of defending the city and its taxpayers in this litigation.”