MEMPHIS, Tenn. (AP) — The family of Tyre Nichols, who died after a brutal beating by five Memphis police officers, sued the officers and the city of Memphis on Wednesday, blaming them for his death and accusing officials of allowing a special unit’s aggressive tactics to go unchecked despite warning signs.

The lawsuit accuses Memphis Police Director Cerelyn “CJ” Davis of starting a crime-suppression unit called Scorpion to target repeat violent offenders in high-crime areas. The lawsuit claims the Scorpion unit used “extreme intimidation, humiliation, and violence” and “disproportionately focused on and targeted young Black men,” adding that this is why Nichols was targeted. It says that the department permitted this aggressive approach to develop and ignored complaints by other residents targeted by the unit before Nichols’ death.

The suit, filed by lawyers for Tyre Nichols’ mother, RowVaughn Wells, seeks a jury trial and financial damages. The five officers charged with beating Nichols were members of the unit, police have said. The unit was disbanded after the Nichols beating.

The city of Memphis declined comment on the lawsuit.

Nichols died three days after the brutal beating in January. It was the latest in a string of violent encounters between police and Black people that have spurred protests and renewed public discussion about police brutality.

In most cases, the officers have been white, but all five officers accused in Nichols’ death are Black. The officers have been charged with second-degree murder.

The lawsuit names as defendants the city of Memphis, Police Director Davis, the five officers who have been fired and charged, another officer who has been fired but not charged, and an additional officer who retired before he could be fired. It also names three Memphis Fire Department employees who were fired after officials said they failed to render aid to Nichols as he was on the ground, struggling with his injuries.

Officers stopped Nichols while he was driving his car for reasons that have “never been substantiated,” the lawsuit said.

Nichols said “What did I do?” during the encounter and ran away from officers after he was pulled out of his car “to attempt to save his life and defend himself,” the lawsuit said.

“While still able to speak, Tyre screamed out for his mother—shouting “Mom! Mom!” into the neighborhood in hopes that she or someone nearby would come to his aid as he was being brutalized and pummeled to death,” it said.

Just feet from his home, Nichols was beaten so badly that he was “left unrecognizable,” the lawsuit states, comparing his case to that of Emmett Till some 70 years prior and the officers to a “modern-day lynch mob.” “Unlike Till, this lynching was carried out by those adorned in department sweatshirts and vests and their actions were sanctioned—expressly and implicitly—by the City of Memphis,” it said.

The five officers’ own body cameras recorded them beating Nichols and then ignoring him for nearly half an hour as the handcuffed and badly injured 29-year-old struggled to stay upright, propped sitting against an unmarked police car.

After the beating, Memphis police on the scene “smiled, laughed, and talked with their fellow officers” as Nichols sat on the ground, the lawsuit said.

Tadarrius Bean, Demetrius Haley, Desmond Mills Jr., Emmitt Martin III and Justin Smith are charged with second-degree murder in Nichols’ death. They have pleaded not guilty.

Martin, Haley, and now-fired officer Preston Hemphill claimed Nichols was driving recklessly before they stopped him as he was heading home from a park the evening of Jan. 7.

They forced Nichols from his car, pinned him to the ground and pepper-sprayed him while threatening to break his arm and fire a stun gun at him. When Nichols managed to run away, Hemphill did fire his stun gun, according to police records.

Nichols was captured a few minutes later by Mills, Bean and Smith. Joined by Haley and Martin, the five officers punched, kicked and pepper-sprayed Nichols and beat him with a baton, according to police records. Memphis Police Director Davis has said she has seen no evidence justifying the traffic stop or the officers’ response. The suit says that the city of Memphis hired Davis as police chief knowing that she had played a prominent role with the Atlanta Police Department’s RED DOG unit: “a police unit that was eventually disbanded due to numerous allegations of violations of the Fourth Amendment to the United States Constitution, including—but not limited to—illegal searches and seizures and excessive force,” according to the lawsuit. The suit accuses Davis of forming an identical unit at the Memphis Police Department that “predictably implemented the same unconstitutional mandates, policies, and customs” The lawsuit calls SCORPION “an officially authorized gang of inexperienced, untrained, hyper-aggressive police officers turned loose on the Memphis community without any oversight.”

Members of the SCORPION unit “engaged in a practice of ‘jumping out’ to ambush Memphis citizens and aggressively harass them and search them in public,” the lawsuit claims. It accuses Davis and other police supervisors of encouraging officers to engage in illegal searches and seizures.

The lawsuit accuses the Memphis Police Department of lowering standards for who could become an officer and making it easier to graduate from the police academy by allowing recruits to retake exams several times at the time the officers involved in Nichols’ beating were brought on. In addition to being less qualified, new recruits were not properly trained in a number of areas, including probable cause, traffic stops, the Fourth Amendment, and use of force, according to the lawsuit.