The ex-officer pleaded guilty to two felony counts, becoming the first to admit culpability in the fatal beating of Mr. Nichols. As part of a plea deal, he is also expected to cooperate with a state murder prosecution.
Medical examiners formally declared his death a homicide, describing severe blunt force injuries to his head and neck as well as bruises and cuts all over his body.
County officials are expected to vote Wednesday on sending Justin J. Pearson back to the state legislature, less than a week after he and a colleague were expelled.