CNN  — 

George Floyd’s brother Philonise had a clear and pressing question for the Minneapolis Police chief on Sunday.

“I want to know if he’s going to get justice for my brother and arrest all the officers and convict them,” he told CNN.

That question regarding the legal fate of the four officers present during Floyd’s death will have vital national significance as widespread protests have continued across the country.

Derek Chauvin, the officer seen kneeling on Floyd’s neck for nearly nine minutes, was charged on Friday with third-degree murder and second-degree manslaughter. Still, three other officers on scene – Thomas Lane, J.A. Kueng and Tou Thao – have not been charged, despite the family’s and protesters’ wishes. All four were fired by Chief Medaria Arradondo last week after video of the incident sparked outrage.

“If that community wants to see the protests stop, this district attorney must step up and do their job,” NAACP President Derrick Johnson told CNN on Sunday. “It’s unfortunate it took so long to indict one person, but all three should be brought to justice.”

The decision is now in the hands of Minnesota Attorney General Keith Ellison, who was appointed Sunday by Gov. Tim Walz to take the lead in the case. Floyd’s family and the Minneapolis City Council had requested Ellison take over the case from Hennepin County Attorney Mike Freeman, CNN affiliate WCCO reported.

Ellison, a former Demoratic congressman, previously said that he had “every expectation” that charges will be filed against the officers and that he hoped they’d come soon.

But on Monday, after taking over the case, he cautioned against a rush to judgement and said prosecutors will be careful and methodical in bringing charges.

“We are moving as expeditiously, quickly and effectively as we can,” he said. “But I need to protect this prosecution. I am not going to create a situation where somebody can say this was a rush to judgement.”

Police chief says officers were ‘complicit’

George Floyd died while in the custody of four Minneapolis Police officers.

Ellison has said that any case against a police officer needs to be airtight given the difficulty of such prosecutions.

Police officers are rarely charged with crimes for violence against black men, and even in those rare cases, juries have repeatedly shown an unwillingness to convict. The list of such failed cases is long.

The officers in Rodney King’s beating were not convicted at their 1992 state trial. In 2014, a grand jury declined to indict the New York Police officer accused of using a chokehold on Eric Garner. The state murder trial of Michael Slager, the officer charged with shooting Walter Scott, ended in 2016 with a hung jury and mistrial. In 2016, none of the six officers charged in Freddie Gray’s death were convicted of wrongdoing. The Minnesota police officer who shot Philando Castile was found not guilty on all counts in 2017.

The few successful prosecutions of officers, including the murder convictions of former Minneapolis Police officer Mohamed Noor and former Dallas Police officer Amber Guyger, had different gender and racial dynamics as well.

Police Chief Arradondo told CNN’s Sara Sidner on Sunday that the silence of the four officers involved in Floyd’s death and their inaction made them “complicit.”

“Being silent or not intervening, to me, you’re complicit. So I don’t see a level of distinction any different,” he said.

“Silence and inaction, you’re complicit. You’re complicit,” he added. “If there were one solitary voice that would have intervened and acted, that’s what I would have hoped for.”

Ellison said Monday he could not comment on the investigation, but he praised Arradondo’s commentary on their inaction.

“I absolutely credit the observations of the chief,” Ellison told CNN. “He has the experience, the know-how, and the integrity to make that comment.”

Ellison’s role is to decide whether that complicity rises to criminality.

Elie Honig, a CNN legal analyst and former federal prosecutor, said the charge against Chauvin was clear just from the cell phone video. However, the criminal case against the other officers will require a more thorough examination of their actions – or lack thereof.

“The key questions are what did each officer see and hear, and what did each officer physically do and say,” he said. “You have to be able to recreate that moment by moment in order to determine whether they’re criminally liable.”

Possible aiding and abetting charge

If the three officers are charged, it would likely be on charges of aiding and abetting, Honig said. The basic idea is that if you help assist, counsel, or facilitate somebody else in committing crime, then you are liable for that crime as well, he explained.

Don Lewis, the special prosecutor in Castile’s case, similarly said aiding and abetting charges are “very likely.” He said he hoped that any such charges are brought within 30 days.

“I do believe you’ve gotta make sure you have the evidence that supports the charges. I do also agree that you have to act urgently,” he said.

Still, he acknowledged that the case against them was not foolproof.

“There is some strong evidence, but there are also some weak points that the defense can take advantage of,” he said.

The statement of probable cause in Chauvin’s criminal complaint provides some hints. The complaint repeatedly notes that the officers did not move from their positions as Chauvin placed his knee on Floyd’s head and neck and as Floyd pleaded that he could not breathe.

One officer, identified as Lane, spoke up several times, the complaint states. While holding Floyd’s legs, he said “should we roll him on his side?” and Chauvin said “No, staying put where we got him,” according to the complaint. Lane then said, “I am worried about excited delirium or whatever,” and Chauvin said “that’s why we have him on his stomach,” the complaint states.

A short time later, after video shows Floyd ceasing to breathe or speak, Lane allegedly said, “want to roll him on his side,” according to the complaint. Kueng checked Floyd’s wrist for a pulse and said he found none, the complaint states. Again, none of the officers moved from their positions.

Chauvin’s knee remained on Floyd’s neck for almost 3 minutes after he became non-responsive, the complaint states. He left the scene in an ambulance and was pronounced dead at Hennepin County Medical Center, the document says.

An independent autopsy found that Floyd died of “asphyxiation from sustained pressure.” The autopsy says compression to Floyd’s neck and back led to a lack of blood flow to his brain.

Ben Crump, the family’s attorney, said the autopsy showed that each of the officers should be arrested.

“Mr. Floyd’s death was a homicide by officers who taunted him while holding him down for more than eight minutes,” he said in a statement. “And the officer who stood by doing nothing was a physical blue shield – a living symbol of the code of silence.”

Correction: This story has been updated with the correct spelling of Tou Thao's name.

CNN’s Amir Vera contributed to this report