The family of a mentally disabled man who was shot and killed by Long Beach police last year filed a federal lawsuit Thursday against the city.

The lawsuit contends Long Beach officers violated Mharloun Saycon’s civil rights by using excessive force and wrongfully killing him. The suit identifies Vuong Nguyen as the officer who shot and killed the 39-year-old.

“These officers need to be held accountable for this unprovoked and despicable attack on an innocent man,” attorney Dan Stormer, who is representing the family, said in a statement. “We believe that Officer Nguyen has so far faced no discipline for this horrific killing.”

A Long Beach police spokesman, Sgt. Brad Johnson, said Nguyen is a 15-year veteran officer and is on active duty with the department. He deferred any other statement about the lawsuit to the Long Beach city attorney’s office. City Atty. Charles Parkin said the agency has yet to review the lawsuit.

Johnson declined to say whether Nguyen had been involved in other shootings, saying The Times would have to submit a formal request under the state’s records law for the information.

Saycon was shot Dec. 4 when two officers responded to a report of a knife-wielding man at Looff’s Lite-A-Line, a gaming parlor, and saw Saycon holding a weapon.

What led to the officer-involved shooting is in dispute.

Long Beach police said Saycon ignored several orders to drop the knife. The officers used a Taser and batons but were unable to subdue Saycon before one of the officers opened fire, the department said after the shooting.

The federal lawsuit alleges the officers were told Saycon suffered from a mental disability but failed to de-escalate the encounter. Instead, the officers entered the building with their weapons drawn as they approached Saycon, who was sitting alone in the front of the arcade casino, watching television with a pocketknife closed on his lap, according to the suit.

“They came into Looff’s aggressively, prepared to attack and kill,” the suit claimed. “Nguyen killed Mharloun even though neither officer was in danger and even though clear alternatives were present to avoid the use of lethal force.”

Saycon was shot in the chest, arm and abdomen and died at the casino. The incident lasted less than a minute after the officers entered the building, according to the suit.

Saycon immigrated to the U.S. from the Philippines in 1985. He was an athlete and honor student at Santa Monica High School and attended Santa Monica College before he was diagnosed with bipolar schizophrenia in his early 20s, according to Saycon’s family.

They said Saycon lived in Carson with his parents and was attending a Compton clinic for people who have mental disabilities.

“There was no reason this had to happen,” Khanly Saycon, Mharloun’s father, said in a statement. “We are bringing this suit to bring some changes to the police force. We want to see justice, for Mharloun and all of the mentally disabled who don’t deserve to die just because they are confused.”

This article was originally published at 11:55 a.m.