A federal civil rights lawsuit filed Tuesday accuses a Fresno police sergeant of shooting an unarmed teenager in the back of the head after he ran from officers during a traffic stop in April last year.

Police have never identified the sergeant who shot 16-year-old Isiah Murrietta-Golding, but the lawsuit in U.S. District Court in Fresno says it is Sgt. Ray Villalvazo, a former homicide detective, who is now a supervisor with the department’s Street Violence Bureau Tactical Team.

The lawsuit accuses police Chief Jerry Dyer, Villalvazo, and the city of Fresno of excessive force, unlawful deadly force, assault and battery, and negligence.

After the lawsuit was filed, Dyer said an internal police investigation determined that “Sgt. Villalvazo’s actions were within department policy.”

He also said Villalvazo remains with the department as supervisor of a tactical team responsible for “locating violent criminals in our city who are wanted.”

The shooting of Murrietta-Golding was justified, Dyer said, because he was wanted for the murder of 19-year-old Eugenio Ybarra that occurred on April, 14, 2017.

A day after Ybarra was killed, Dyer said, Murrietta-Golding ran from a car that had been stopped by police. Officers believed he was armed with a handgun that was used in the killing of Ybarra.

While police were chasing Murrieta-Golding, he “reached into his waistband several times,” Dyer said. After he jumped a fence and entered the rear of a daycare, Murrietta once again reached into his waistband, while looking back at Villalvazo the chief said.

“Fearing he was about to be shot, Sgt. Villalvazo fired one round, striking Murrietta-Golding,” Dyer said.

After Murrietta-Golding was shot by police, his 17-year-old brother surrendered to police and was booked into Fresno County’s Juvenile Justice Center in connection with the killing of Ybarra. Because he is a juvenile, his name and his court proceedings are confidential.

Assistant District Attorney Steve Wright said the office is still investigating the officer-involved shooting.

At the time of the shooting, Dyer said Murrietta-Golding and his brother are associated with the Calwa Bulldogs gang and Ybarra was associated with a rival tagging crew.

Oakland attorney Michael J. Haddad , who filed the lawsuit on behalf of Murrietta-Golding’s mother, Christina Pauline Lopez, said Dyer has a habit of defaming minorities who get shot by police. He said Murrietta-Golding, a 10th-grader, was a good student at Carter G. Woodson, a public charter school in Fresno, and a teen who liked to play video games with his siblings and sports.

“Isiah had no tattoos and was not in a gang,” Haddad said. “He was a little boy.”

Haddad said if Murrietta-Golding was involved in the shooting of Ybarra, police could have gotten a warrant for his arrest. But when Murrietta-Golding was shot, police didn’t have a warrant, Haddad said.

Dyer has said police have a video of Murrietta-Golding being chased by police, but not the shooting. Haddad said he and the teen’s family have asked for a copy of the video and investigative reports, but their requests have been denied.

“They deserve to know what happened,” he said.

In the lawsuit, Haddad and Lopez are seeking unspecified damages for wrongful death, medical and burial expenses, loss of love and emotional distress.

Fresno attorney Stuart Chandler said he plans to file a similar suit on behalf of the boy’s father, Anthony Golding.

Court records say Haddad has prevailed before in a similar civil rights lawsuit against the Fresno Police Department. In November 2016, the city agreed to pay $2.2 million to Haddad’s client -- the family of Jaime Reyes Jr., 28, who was fatally shot while running from police in June 2012.

Haddad said his lawsuit relies on information that police have already made public:

On April 14, four young men got into an argument with the two brothers near a pizza parlor at First Street and Gettysburg Avenue in central Fresno. As the four young men drove off, one of the two teens fired a handgun at the car as it drove south on First Street.

“According to the FPD, none of the shots struck either the driver or the three other passengers, but gunshots did hit the car,” the lawsuit says. The gunfire caused the car to crash into a tree, killing the driver, Ybarra. His three passengers were taken to the hospital.

The next day, the Street Violence Bureau staked out a house on the 500 block of East San Bruno Avenue near Fresno Street and Barstow Avenue, where the two brothers lived. The lawsuit says the Street Violence Bureau is a tactical team of of plainclothes officers who engages in aggressive, proactive policing.

The lawsuit says police did not enter the home because they did not have an arrest warrant or a search warrant.

Around 3:30 p.m. a car with three teens left the San Bruno home, prompting the tactical team to make a “high-risk” traffic stop in the parking lot of the Gallery Plaza at Shaw Avenue and First Street. The lawsuit says the three teens initially complied with police commands to walk backwards with their hands raised while Villalvazo and other officers held them at gunpoint.

Murrietta-Golding then took off, running across Fresno Street. “Isiah was unarmed and holding a hat in his right hand,” the lawsuit says. The two other teens did not run.

Villalvazo chased Murrietta-Golding as he ran toward the New Life Discovery preschool at First and Keats Avenue., north of Shaw Avenue. Because it was Saturday, the preschool was closed and the parking lot was empty, the lawsuit says.

Murrietta-Golding jump a fence and ran toward the preschool. Villalvazo did not climb over the fence. Instead, “Sgt. Villalvazo aimed his duty weapon at the back of Isiah’s head,” the lawsuit says. “Sgt. Villalvazo fired a single shot, which tore through Isiahs’ occipital lobe.”

The lawsuit says Villalvazo had no legal justification to draw his weapon when the teens were pulled over or when Murrietta-Golding took off running. Villalvazo also failed to give any warning to Murrietta-Golding before “using deadly force,” the lawsuit says. “Villalvazo had no facts to believe Isiah was armed or had any intent to harm anyone.”

Murrietta-Golding was 5-feet-4-inches tall and 109 pounds. As he ran from police, his loose-fitting pants or shorts fell down. He may have reached with his left hand to pull up his clothing or glanced backward to see Villalvazo, the lawsuit says, but “no reasonable officer would have interpreted either movement as posing an immediate threat to anyone’s safety.”

Wounded and laying on the ground, Murrietta-Golding needed urgent medical care. Instead, Villalvazo and the other officers frisked and handcuffed Murrietta-Golding, the lawsuit says. Several minutes passed before Villlvazo and the others sought first aid for Murrietta-Golding., the lawsuit says.

An unconscious Murrietta-Golding was taken to the hospital in handcuffs, despite requests from ambulance staff to remove them, the lawsuit says. The handcuffs were taken off at the hospital, where Murrietta-Golding remained in critical condition until he died three days later.