The charges against the police officers involved in the killing of George Floyd - including an upgraded charge for former Minneapolis police officer Derek Chauvin - were announced by the state's attorney general on Wednesday.
Minnesota Attorney General Keith Ellison announced that Mr Chauvin's charges were being upgraded to second degree unintentional murder, and that the other officers involved - Thomas Lane, Alexander Kueng, and Tou Thao - had been charged with aiding and abetting a murder.
According to the state's sentencing guidelines, second degree unintentional murder carries a recommended sentencing of 12 years in prison. The maximum sentence for the charge is 40 years in prison. The maximum charge for those convicted of aiding and abetting murder in the state is also 40 years incarceration.
Mr Chauvin was originally charged with third degree murder, which carried a maximum of 25 years in prison and a recommended sentence of 12 years.
"I believe the evidence available to us now supports the stronger charge of second-degree murder," Mr Ellison said during a press conference.
He said that additional information regarding the cases was unlikely to be released as the investigation continues. However, the charges did come after the findings of an independent autopsy ordered by the family concluded that Mr Floyd died from asphyxiation.
Joe Kennedy, a law professor at the University of North Carolina School of Law, said that charges can be changed or upgraded in light of new evidence or after prosecutors revisit the law and change their original determinations about a charge.
He said that in typical cases, prosecutors tend to file the maximum possible charge to pressure defendants and provide leverage for negotiating plea deals, but he said "all bets are off in a high profile case."
"I think prosecutors began with a third degree murder charge because it was a 'safe charge' in terms of being easiest to prove at trial, and because obtaining murder convictions of any sort against police officers for excessive force is historically supremely difficult."
The likelihood of a conviction in Mr Chauvin's case is up in the air; Mr Ellison said it would likely be difficult to win the case.
"Every single link in the prosecutorial chain must be strong. It needs to be strong because trying this case will not be an easy thing. Winning a conviction will be hard," Mr Ellison said.
Winning convictions against police - when officers are actually convicted for killing people - is infrequent, and often when they are convicted, their charges tend to be minimal.
"Prosecutors are historically reluctant to charge police cases," Mr Kennedy said. "Juries are historically reluctant to return even manslaughter convictions against police officers in excess of force cases."
Mr Kennedy said that aiming for second degree murder also makes it more possible that juries will agree to a 'compromise sentence' of third degree murder should the prosecution fail to fully convince them of his motives. However, he also noted that an anomaly in Minnesota's criminal homicide statue could make convicting Mr Chauvin on second degree murder an easier prospect than it would be in other states.
"Something really weird about Minnesota's criminal homicide statute is that their second degree murder charge is essentially a felony murder charge," he said. "The idea is 'well, you intentionally committed this felonious assault and someone died.' The vast majority of states don't allow you to use felony murder in that way, because that would make potentially any felonious assault a murder."
Mr Kennedy used a bar fight as a metaphor. Suppose a man starts a fight in a bar with another person, and during that fight things get out of hand and the person dies. In most states, a prosecutor trying the man for murder would have to prove there was intent behind his actions to convict him on murder. If intent could not be established, he'd be tried and likely convicted of manslaughter.
However, under Minnesota law, that death - resulting from a felonious assault - could be tried as a second degree unintentional murder, the charge Mr Chauvin is facing.
"It makes it a lot easier to get a second degree murder charge, because all they have to prove is 'well look, [Chauvin] knew he was assaulting [Floyd], he knew the force was excessive. He was seriously hurting the guy, seriously injuring him, and he knew he didn't have to. And he died," Mr Kennedy said. "That's where causation comes in, and that's a lot easier to prove that proving I intended to kill someone."
As for the other three officers, prosecutors will have to prove that either the cops' actions encouraged or assisted the murder, or that their failure to act when they had a legal duty to intervene could have prevented the murder.
In addition to the upgraded charges Mr Chauvin is facing and the new charges faced by the other three officers, the potential for federal charges - and harsher sentences - is still looming over the case.
According to the US Justice Department, the FBI is currently investigating whether the officers violated Mr Floyd's civil rights during the arrest and subsequent killing. If federal authorities chose to charge Mr Chauvin with violating Mr Floyd's civil rights, he could face a up to a life sentence.
"In the federal system, when somebody's constitutional rights have been violated and there's a death that occurs, then the feds take the case," Dr David Thomas, a professor of forensic psychology at Florida Golf Coast University and a 20-year retired police officer, said. "A Civil rights violation is far greater and carries a lot of impact. And so if they can get those charges, it's easier to convict an officer than on murder."
Under federal law, anyone found guilty of depriving someone of their constitutional rights resulting in their deaths can face up to life in prison or be sentenced to death.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies