MINNEAPOLIS (AP) — Prosecutors charged a Minneapolis police officer accused of pressing his knee against George Floyd’s neck with a more serious charge of second-degree murder on Wednesday, and for the first time leveled charges against three other officers, issuing warrants for their arrests.

An updated criminal complaint against Derek Chauvin says his actions were a “substantial causal factor in Mr. Floyd losing consciousness, constituting substantial bodily harm, and Mr. Floyd’s death as well.” The unintentional second-degree murder count carries a maximum penalty of 40 years in prison, compared with 25 years for third-degree murder.

“I believe the evidence available to us now supports the stronger charge of second-degree murder,” said Minnesota Attorney General Keith Ellison. The complaints against the other officers accuse them of aiding and abetting Chauvin’s actions and of manslaughter.

Widely seen bystander video showing Chauvin pressing his knee into Floyd's neck on May 25 has sparked protests nationwide and around the world against police brutality and discrimination.

All four officers were fired and Chauvin was initially charged with third-degree murder and second-degree manslaughter. The three other officers involved were not immediately charged, spurring calls from protesters and Floyd's family for them to also face criminal charges.

The unintentional second-degree murder charge alleges that Chauvin caused Floyd's death without intent while committing another felony offense, namely third-degree assault. For the other defendants — Thomas Lane, J. Kueng and Tou Thao — aiding and abetting is legally tantamount to committing the same acts as Chauvin, so they will face the same penalties if convicted.

The multiple charges against each defendant would give a jury more opportunity to find them guilty.

“George Floyd mattered. He was loved, his family was important, his life had value, and we will seek justice for him and for you, and we will find it," Ellison said during a news conference.

Attorney Earl Gray, who represents Lane, told The Associated Press that he hadn't seen the complaint or talked with his client. He said Lane was not in custody. Before news of the upgraded charges, an attorney for Chauvin declined to comment and attorneys for Thao and Kueng didn't respond to requests for comment.

Jail records show Kueng was in custody Wednesday afternoon. Authorities expected Lane and Thao to also be arrested. Chauvin has been in custody since last week.

Attorney Ben Crump tweeted that the Floyd family was “deeply gratified” by the new charges, calling them “a source of peace for George’s family in this difficult time.” He said Ellison had told the family his office will continue to investigate and upgrade charges against Chauvin to first-degree murder if warranted.

“I promise to hold everyone accountable for the behavior that we can prove in a court,” Ellison said. “And if I don’t charge it, it means that we did not have the facts to do that.”

Ellison said public pressure had no effect on his decision to file charges and acknowledged that winning a conviction against a police officer is hard.

The narratives in the other three complaints are almost identical to the one against Chauvin. The complaint against Lane notes that he asked about rolling Floyd on his side and wondered about delirium, but goes on to say: “Despite his comments, the defendant took no actions to assist Mr. Floyd, to change his position, or to reduce the force the officers were using against Mr. Floyd.”

The complaint against Kueng says he was positioned between Chauvin and Lane and could hear their comments. The complaint against Thao, who was seen in the bystander video standing near a crowd of bystanders, says Thao initially got a hobble restraint from the squad car, “but the officers decided not to use it and maintained their positions.”

Personnel records released by the city show Chauvin served as a military policeman in the U.S. Army in the late 1990s. Since being hired as a police officer in 2001, he has been awarded two medals of valor: One for being part of a group of officers who opened fire on a stabbing suspect after the man pointed a shotgun at them in 2006, and one for apprehending another man in a domestic incident in 2008. In the latter incident, Chauvin broke down a bathroom door and shot the man in the stomach.

Chauvin was reprimanded in 2008 for pulling a woman out of her car in 2007, frisking her and placing her in his squad car after he stopped her for speeding 10 miles per hour over the limit. His dashboard camera was not activated and a report said he could have interviewed the woman while standing outside her car.

Lane, 37, and Kueng, 26, both joined the department in February 2019 and neither have any complaints on their files.

Lane previously worked as a correctional officer at the Hennepin County juvenile jail and as a probation officer at a residential treatment facility for adolescent boys.

Kueng was a 2018 graduate of the University of Minnesota where he worked part-time on campus security. He also worked as a theft-prevention officer at Macy’s in downtown Minneapolis while he was in college.

Thao, a native Hmong speaker, joined the police force as a part-time community service officer in 2008 and was promoted to police officer in 2009. He was laid off later that year due to budget cuts and rehired in 2012.

Gov. Tim Walz and the Minnesota Department of Human Rights on Tuesday launched a civil rights investigation of the Minneapolis Police Department and its history of racial discrimination, in hopes of forcing widespread change.

___

Associated Press reporters Scott Bauer and Todd Richmond in Madison, Wisconsin, and Bernard Condon and Michael Sisak in New York contributed to this report.