*(CNN) — One of the five former Memphis police officers accused in the January death of Tyre Nichols pleaded guilty Thursday to federal charges and agreed to plead guilty to related state charges as part of a plea deal with prosecutors. Desmond Mills Jr., 33, pleaded guilty to two of the four federal charges he was facing, according to the US Attorney’s Office for the Western District of Tennessee. He also agreed to plead guilty in state court at an upcoming hearing on charges related to Nichols’ death, according to the Shelby County district attorney.
Mills pleaded guilty to civil rights and conspiracy charges, which included using excessive force and failing to intervene, as well as conspiring to cover up his use of unlawful force, the US attorney’s office said.
As part of the agreement, he will be called to testify against the other defendants, according to prosecutors. He has also agreed to fully cooperate in the federal civil rights investigation into patterns and practices of the Memphis Police Department.
Mills agreed to have both his state and federal cases resolved in exchange for his cooperation in the cases of four fellow ex-officers: Tadarrius Bean, Justin Smith, Emmitt Martin III and Demetrius Haley. They have all pleaded not guilty.
Shelby County District Attorney Steve Mulroy said in a news conference that state and federal prosecutors will recommend to a judge that Mills serve 15 years in prison, though the decision is ultimately up to the judge.
