ABC News(MINNEAPOLIS) — BY: CHRISTINA CARREGA and WHITNEY LLOYDA week after George Floyd was seen on a bystander’s cellphone video gasping his last breaths with the knee of a former Minneapolis police officer pinned on his neck, three of the four former officers at the scene hadn’t been charged.That changed on Wednesday.Thomas Lane, J.A. Kueng and Tou Thoa each have been charged with second-degree aiding and abetting felony murder and second-degree aiding and abetting manslaughter, according to court documents. Charges against Derek Chauvin, who on May 29 was charged by Hennepin County prosecutors with third-degree murder and second-degree manslaughter, have been upgraded to second-degree murder. Chauvin is in jail on $500,000 bond.All four officers were fired from the Minneapolis Police Department in the wake of Floyd’s death.Minnesota Attorney General Keith Ellison is expected to give an update on Wednesday afternoon.Ben Crump, an attorney for the Floyd family, has demanded that Kueng, Lane and Thoa are charged with acting in concert with Chauvin allegedly to murder Floyd.Minnesota attorney Jay Adkins told ABC News on Wednesday that the third-degree murder charges against Chauvin may have failed at trial.“The third-degree murder charges…is invalid in this case because the officer’s actions were directed only to Mr. Floyd not multiple people — like firing in a crowded building,” said Adkins, who cited a Minnesota Supreme Court case that reads “third-degree murder ‘cannot occur where the defendant’s actions were focused on a specific person.’”“The importance of the new second degree charges against former officer Chauvin. If the elevated charges don’t result in a conviction, the likely results would be a conviction to a form of manslaughter, not murder,” Adkins said.According to arrest warrant documents, Chauvin pinned his knee onto the back of Floyd’s neck for eight minutes and 46 seconds.During that time, Lane asked Chauvin whether Floyd should get rolled onto his side, but Chauvin refused to move him, according to the warrant. Lane allegedly was holding Floyd’s legs as Kueng allegedly was holding Floyd’s back down as Chauvin kept his knee in place, according to the arrest warrant. Thoa was seen on the video with both of his hands in his pockets.“Based on … their silence and based on their body cameras and audio, we know they did nothing … they all participated in the death of George Floyd,” Crump said at a press conference on Wednesday before the new charges were announced.A bystander recorded the incident on a cell phone. Floyd can be heard repeating pleading, “I can’t breathe,” and for his mother, who died years ago.An independent autopsy determined Floyd’s cause of death was by asphyxia “due to neck and back compression that led to a lack of blood flow to the brain.” The county’s medical examiner ruled that Floyd died because of a cardiopulmonary arrest.Crump said in a statement that Ellison informed the Floyd family “that his office will continue to investigate and will upgrade the charges to first-degree murder if the evidence supports it.”Copyright © 2020, ABC Audio. All rights reserved.