During a news conference on Friday, the family said they want justice, and they want changes to the way police officers are trained, and the way officer-involved shootings are investigated.
Michael Nida, a father of four, was killed on Oct. 22. Police were looking for armed robbery suspects in the area of Paramount Boulevard and Imperial Highway. Authorities said Nida had clothing similar to the suspect description.
The family said Nida was with his wife pumping gas and ran across the street to buy cigarettes. Investigators claim Nida ran from the officers who were trying to detain him.
When he turned toward them, one of the officers opened fire, police said, but the family said Nida was shot in the back and had done nothing wrong.
"My brother was not a criminal. He was not a gang member. He did nothing wrong that night," said sister Terri Teramura.
The attorney for the family alleges the same police officer who killed Nida has a history of violence. Downey police said they have no response to that claim.
"The police officers should not be the judge, the jurors and the executioner, and somebody needs to make a change in the police department," said mother Jean Thaxton.
The department later determined Nida was not armed, and they do not believe he was involved in the robbery.
The Nida family and their attorney say Downey should form a citizens review committee of volunteers to review use-of-force investigations, and then report their findings to the chief of police.
The officer involved in Nida's death remains on administrative leave.
Nida's family members plan to hold a march and rally on Saturday that begins at Paramount Boulevard and Imperial Highway and ends at the police department.