As the trial of former Minneapolis police officer Derek Chauvin in the death of George Floyd headed into its second week, the Democratic congresswoman Ilhan Omar said residents remain “on edge” about the outcome. On Sunday on CNN’s State of the Union, Omar was reminded that few trials involving police officers result in conviction, and asked: “Are you and your city prepared for the possibility of a hung jury or a not-guilty verdict?” “The community is on edge about that,” Omar said. “We have seen justice not delivered in our community for many years. I think that there is a lot of confidence in [state] attorney general Keith Ellison and the prosecutors in this case, but we are all eagerly awaiting to see how this trial shakes out. “It’s been really horrendous to watch the defense put George Floyd on trial instead of the former police officer who’s charged with his murder.” Floyd, 46, died last May when Chauvin kneeled on his neck for more than nine minutes during an arrest. The killing sparked international protests against police brutality and racial injustice. The vast majority of protests were peaceful but in Minneapolis and other cities some became violent. Chauvin faces charges of second-degree unintentional murder, third-degree murder and second-degree manslaughter. He has pleaded not guilty. Three other officers will face separate trials. On Monday, prosecutors are expected to call police department chief Medaria Arradondo as a witness. It is rare, if not unheard of, for a police chief to testify against a former officer. Experts have said Arradondo’s testimony might open the door to more chiefs being called in future. “He is going to tell you that Mr Chauvin’s conduct was not consistent with Minneapolis police department training,” prosecutor Jerry Blackwell told jurors in his opening statement. “He will not mince any words. He’s very clear. He will be very decisive: that this was excessive force.” Arradondo’s testimony is expected to be a powerful tool for prosecutors as they seek to refute the defense claim that Chauvin’s decision to kneel on Floyd’s neck was in keeping with use-of-force guidance. Dr Cedric Alexander, a former police chief and public safety director of DeKalb county, Georgia, told the Guardian this week calling Arradondo was a “pretty remarkable move on the part of the prosecution”. “It’s very rare that you’re going to see a chief either appear for the defense or the prosecution,” he said. “But each one of these kinds of events brings its own set of circumstances. And in this particular case, where you have a knee to the neck and it’s being questioned, ‘Was that trained technique?’ To be able to have the chief of police … to under-oath testify is clearly going to be of importance.” Laurie Robinson, a former assistant US attorney general who co-chaired Barack Obama’s Taskforce on 21st-Century Policing, which was launched after the shooting death of Michael Brown in Ferguson, Missouri in 2014, said: “The chief is under tremendous pressure. “This may be the hardest police chief job in the country at this point, between the tensions around this trial, pressures from the community dealing with the aftermath of the George Floyd death, the calls for changes in the department and the protection of the community that’s dealing with rising gun violence and crime.” Arradondo will not be the only Minneapolis officer to testify that Chauvin’s actions strayed from department policy. Lt Richard Zimmerman, who leads the homicide department, testified on Friday that in four decades on the force, he had never been trained to restrain an arrestee with a knee to the neck. “If your knee is on a person’s neck, that can kill them,” he said. “Once a person is cuffed, the threat level goes down all the way. They’re cuffed, how can they really hurt you?” Floyd was handcuffed before police forced him to the ground. “I saw no reason why the officers felt they were in danger, if that’s what they felt,” Zimmerman said. “And that is what they have to feel to use that level of force.” Zimmerman was among 14 officers who released a letter to Minneapolis residents a month after Floyd’s death, saying they “wholeheartedly condemned” Chauvin’s behavior. Many in the city found the first week of the trial traumatic, as witnesses spoke and video of Floyd’s death was shown. “It’s been really hard,” Omar told CNN. “I think the one part that stayed with me is the fact that everyone who took the witness stand said they felt helpless. That is a feeling that we know really well here in Minneapolis when it comes to police abuse. “…[The trial] has just unearthed so much trauma for for many of us. But we have each other. And we’re gonna get through it.”