The former Minneapolis police officer charged with killing George Floyd went on trial Monday, with a prosecutor telling the jury that the figure to remember is nine minutes, 29 seconds — the amount of time Derek Chauvin’s knee was on Floyd’s neck as the black man pleaded for his life and went limp. Prosecutor Jerry Blackwell told jurors that Chauvin “didn’t let up, he didn’t get up” even after Floyd said 27 times that he couldn’t breathe and went motionless. He said bystander witnesses would include a Minneapolis Fire Department first responder who wanted to administer aid. He said Chauvin pointed Mace at her. “She wanted to check on his pulse, check on Mr. Floyd’s well-being,” Blackwell said. “She did her best to intervene. When she approached Mr. Chauvin …. Mr. Chauvin reached for his Mace and pointed it in her direction. She couldn’t help.” Unintentional second-degree murder is punishable by up to 40 years in prison in Minnesota, with up to 25 years for third-degree murder, but sentencing guidelines suggest that Chauvin would face 12 1/2 years in prison if convicted on either charge.