In the lawsuit, attorneys for Ramirez's family say he was cooperating with police and was standing with his hands up when an officer approached him from behind and shot him in the back of his head.

The officers then "created a blatantly false story" that Ramirez had a knife, the suit says.

Dana Douglas, an attorney representing the family, said investigators hired by her law firm had spoken to a witness to the shooting, someone who lives in an apartment nearby, who said Ramirez had his hands up.

However, people in the neighborhood are afraid to speak up, and "we're not confident" that the witness will testify in court, said James Rumm, another attorney representing the family.