A federal prosecutor in Minnesota who was investigating an Immigration and Customs Enforcement officer for possible civil rights crimes has been fired, four sources familiar with the matter told CBS News. Assistant U.S. Attorney Matthew Evans was investigating ICE officer Christian Castro for the shooting of a Venezuelan immigrant earlier this year. The Justice Department finally charged Castro this week with making false statements about the incident, but the indictment remains sealed, CBS News previously reported. Earlier this week, ProPublica reported that Evans told lawyers for the man who was shot, Julio Cesar Sosa-Celis, and other victims to prepare for Castro to only be charged with making false statements, which would carry lesser penalties than criminal charges for violating people’s constitutional rights under color of law. ProPublica directly cited an email it said Evans had sent to lawyers. “This is being directed by the chief judge and the federal prosecutor,” Evans’ email allegedly said. “I objected in the strongest terms possible and fought as hard as I could. It wasn’t enough.” (CBS News has not obtained the email reviewed by ProPublica.) Three sources told CBS News that Evans is under investigation by the Justice Department. Two sources said the investigation is focused on allegations of leaks. CBS News has reached out to Evans for comment. A federal grand jury returned a six-count indictment against Castro on Wednesday, multiple sources familiar with the matter told CBS News. He was arrested in Texas on Thursday and will initially appear in court on Friday, a source said. The case revolves around an incident in January involving Castro and Sosa-Celis, who officials say is in the United States illegally, during the Trump administration’s immigration crackdown in the Minneapolis area. After Sosa-Celis was shot in the leg, federal prosecutors charged him and another man, Alfredo Alejandro Aljorna, with forcibly assaulting, resisting or impeding federal agents. But the federal government’s description of the events leading up to the shooting has changed, and ICE later accused its agents of lying about the incident. Initially, the Department of Homeland Security said Sosa-Celis fled on foot from a traffic stop, and when an ICE agent attempted to arrest him, two other men attacked the agent with a shovel and broomstick. DHS said Sosa-Celis then broke free and began attacking the agent as well, prompting the agent to fire a “defensive shot to defend his life.” But an FBI affidavit filed in the criminal case against Sosa-Celis and Aljorna alleged that Aljorna, not Sosa-Celis, was the one who fled a traffic stop, and said Sosa-Celis had initially hit the ICE agent with a broomstick while the agent was trying to arrest Aljorna. The officer described it as a fight that lasted three minutes, according to the affidavit. Cellphone video shared by a Democratic state senator also showed a woman telling 911 that her husband was chased by ICE agents before arriving home, and was shot in front of his family. And a video later published by The New York Times showed that the altercation involving Aljorna and Sosa-Celis lasted much less than three minutes. A month after Aljorna and Sosa-Celis were charged, the Justice Department dropped the case, saying the “newly discovered evidence” was “materially inconsistent” with the allegations against them. Todd Lyons, who headed ICE at the time, said a review of video evidence showed that two ICE officers had made “false statements” in sworn testimony. He said the officers would be placed on administrative leave and could face prosecution. Castro, the ICE agent who shot Sosa-Celis, was indicted in May on state charges of assault and false reporting of a crime, and was arrested in Texas. But Texas Gov. Greg Abbott refused to extradite him to Minnesota, sparking a legal battle that ended with Castro’s release from a Texas jail last week. More from CBS News Go deeper with The Free Press