Prosecutors charged a Minnesota state trooper with second-degree murder on Wednesday in the fatal shooting of a motorist who drove away during a traffic stop last summer in Minneapolis.
The announcement of charges against Trooper Ryan Londregan in the death of the driver, Ricky Cobb II, followed an investigation that exposed tensions between law enforcement officials and prosecutors.
Trooper Londregan is the first law enforcement officer whom Mary Moriarty, the top prosecutor in Hennepin County, which includes Minneapolis, has charged in an on-duty shooting. Ms. Moriarty, a former public defender, was elected in 2022 and has promised sweeping changes in the wake of the 2020 murder of George Floyd, including stronger efforts to hold officers accountable for misconduct.
Legal experts say that prosecutors have become more willing to charge law enforcement officials since Mr. Floyd was killed by a Minneapolis police officer, sparking a national outcry over police abuses and racism. Even so, criminal charges in such cases remain rare, and when they are brought, prosecutors struggle to secure convictions.
In addition to the second-degree murder charge, Trooper Londregan was charged with first degree assault and second-degree manslaughter.
Peter B. Wold, a lawyer for Trooper Londregan, 27, did not immediately comment on the charges.
Mr. Cobb, a 33-year-old Black man, was fatally shot on July 31 after state troopers including Trooper Londregan, who is white, pulled him over on Interstate 94 for driving without working taillights, according to the Minnesota Department of Public Safety.
During the stop, the troopers determined that Mr. Cobb was subject to arrest over a suspected violation of a protective order involving a former romantic partner, officials said.
Police body-camera footage released shortly after the shooting showed the sequence of events.
Trooper Brett Seide, one of three officers at the scene, asked Mr. Cobb to get out of his car as Trooper Seide stood by the driver’s side door. Mr. Cobb, who was alone in the car, can be heard questioning the request and demanding to know whether there was a warrant for his arrest.
Trooper Londregan, who was standing on the passenger’s side of the car, can be seen opening the door and reaching inside in an effort to force Mr. Cobb out, the body-camera footage shows. Trooper Seide did the same on the driver’s side. Almost immediately, Mr. Cobb’s vehicle can be seen lurching forward.
When the car began moving, Trooper Londregan fired his handgun twice, striking Mr. Cobb in the torso, officials said. Troopers Seide and Londregan tumbled to the ground as the car sped off.
Mr. Cobb drove for about a quarter-mile before his car came to a stop on the side of the highway. He died at the scene, officials said.
At the time of the traffic stop, Trooper Londregan had been a law enforcement officer for about a year and a half. He is now on paid leave.
Prosecutors said the troopers’ actions that night were at odds with how they are trained to remove an uncooperative person from a vehicle. As a matter of policy, the prosecution’s charging document said, “troopers should make every effort not to place themselves in a position that would increase the possibility that the vehicle they are approaching can be used as a deadly weapon.”
Investigators who searched Mr. Cobb’s vehicle after his death found a handgun on the floor behind the center console, according to the Bureau of Criminal Apprehension, the state agency that investigates police shootings.
The gun was not visible in the police body-camera video, and no evidence has emerged publicly to suggest that the troopers knew there was a gun in the vehicle before Mr. Cobb’s death. Mr. Cobb was not permitted to legally possess a gun in Wisconsin because he had been convicted of domestic assault in 2017, according to court records.
Soon after his death, Mr. Cobb’s relatives and civil rights activists in Minnesota called on elected officials to fire and criminally charge the troopers involved. Relatives of Mr. Cobb met in August with Gov. Tim Walz, a Democrat, and separately with Ms. Moriarty.
The union that represents state troopers called the meeting with the governor “improper,” arguing that it could unduly influence the criminal investigation.
As prosecutors began investigating the killing, Ms. Moriarty said her office was being stymied by State Patrol officials who refused to cooperate.
In recent years, Minnesota prosecutors have tended to present cases involving police use of deadly force to grand juries, leaving them to determine whether an officer’s conduct amounted to a crime. In the Minneapolis area, prosecutors have often asked a county attorney in a different county or the state attorney general to handle police deadly-force cases.
When she was running for office, Ms. Moriarty said she disliked those arrangements. Her campaign website promised that if elected, she would make determinations about charging police officers herself, in order to “let the people of Hennepin County hold her accountable for those decisions.”
In this case, Ms. Moriarty said the decision to file charges was made by her and her team rather than by a grand jury.
Ms. Moriarty said that Wednesday was a difficult day for the families of Mr. Cobb and Trooper Londregan.
“Our community continues to navigate the compounding trauma and grief that results from the tragic loss of our community members at the hands of police,” she said.