Story highlights "The evidence has not changed, but the presentation of that evidence will," Anthony Gray says

In the civil case, a jury will make a decision based on a lower burden of proof

Word of the lawsuit comes six weeks after the Justice Department declines to charge Officer Darren Wilson

(CNN) The family of Michael Brown has filed a civil lawsuit against the city of Ferguson under Missouri's "wrongful death statute," family attorney Benjamin Crump said in a statement Thursday.

The suit seeks punitive and compensatory damages in excess of $75,000, in addition to attorney fees.

Brown's parents attended a news conference in front of the St. Louis County Courthouse after the suit was filed. His mother, Lesley McSpadden, who wore a red hoodie bearing her son's likeness, and his father, Mike Brown Sr., wearing a St. Louis Cardinals snapback and a hoodie that said, "Mike Brown chosen for change," did not speak, allowing attorneys Anthony Gray and Crump to address reporters.

In addition to the city, the suit also names Officer Darren Wilson, whose fatal shooting of Brown has been ruled justified, and former police Chief Thomas Jackson, who resigned last month.

Wilson "unjustifiably shot and killed (Brown), using an unnecessary and unreasonable amount (of) force in violation of (Brown's) constitutionally guaranteed right to life," the lawsuit states.

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