A former Oxford University employee accused of fatally stabbing a man in Chicago has pleaded guilty, it was announced on Thursday.

Andrew Warren, who was a treasury assistant at Somerville College at the time of the murder, attacked his victim while he was sleeping, according to a plea agreement released by the court.

Warren also agreed to give evidence against his co-defendant, Wyndham Lathem, in exchange for a lesser sentence of 45 years.

The pair were charged with first-degree murder for the killing of Trenton Cornell-Duranleau. A hair stylist from Michigan, his body was found with his throat slit and 70 stab wounds in July 2017.

A nationwide manhunt was launched for Warren and the former Northwestern Professor, Wyndham Lathem, who lived in the apartment and was identified as Cornell-Duranleau’s boyfriend.

After the body of Mr Cornell-Duranleau was found, Warren was suspended and subsequently fired from his job at Somerville College.

Natosha Toller, an assistant state attorne in Chicago, described the plan as a sexual fantasy. Warren and Lathem began communicating online in the month before the murder.

Abandoning the original plan to commit suicide following the murder, the pair fled Chicago and headed to California, stopping at a public library in which they made large donations in Cornell-Duranleau’s name.

Warren eventually handed himself in after eight days on the run in San Francisco, and Lathem gave himself up in Oakland.

Somerville College has been contacted for a comment.