The Northwestern professor and University of Oxford employee accused of killing a young man in Chicago last month were carrying out a violent sexual fantasy, prosecutors said Sunday. Wyndham Lathem and Andrew Warren both admitted to the gruesome killing of 26-year-old Trenton Cornell-Duranleau.

Lathem, a 43-year-old former associate professor of microbiology and immunology at Northwestern University in Chicago, and Warren, a 56-year-old senior treasury assistant for payroll and pensions at a branch of the University of Oxford in England, first entangled themselves in the sinister fantasy through online chat rooms.

The two men exchanged their fantasies online about killing other people before taking their own lives, Assistant State's Attorney Natosha Toller said in court Sunday. The pair hatched a plan in which they would lure Cornell-Duranleau, Lathem's boyfriend, to his apartment and kill him. They also planned to kill a victim of Warren's choosing before simultaneously killing each other. Lathem paid for Warren's travel to the United States so they could carry out their scheme.

"What I can tell you, it was not domestic in nature, like a husband/wife or boyfriend/boyfriend or love triangle, that was not the motive," Chicago police Detective Cmdr. Brendan Deenihan said at a press conference Sunday. "It was a little more dark and disturbing."

On July 26, they put their plan into action. After Cornell-Duranleau fell asleep in Lathem's apartment, Lathem repeatedly stabbed him while instructing Warren to record the murder. When Cornell-Duranleau started to fight back, Warren hit him in the head with a metal lamp, the Chicago Tribune reported Monday. Police said Cornell-Duranleau was nearly decapitated and had been stabbed so severely 70 times, the blade snapped off the knife.

"Defendant Warren told the police that the victim had no idea what was coming," Toller said Sunday, according to the Chicago-Tribune.

The pair also planned to kill another person of Warren's choosing, though it remained unclear whether the second would-be victim ever showed up at the apartment.

After Cornell-Duranleau's murder, Lathem and Warren quickly showered and tried to clean up the scene before fleeing. As they headed west to California, Lathem recorded a video he sent to friends and family in which he referred to "the biggest mistake of his life." The pair also made two donations to charity in Cornell-Duranleau's name: one for $5,610 to an LGBT health center and another for $1,000 to a public library. It was Lathem who tipped police off that something sinister had occurred inside his home: the ex-professor called the apartment building and left an anonymous tip about a crime having been committed inside his unit.

Both men surrendered in California nine days after the slaying. Lathem was arrested outside a federal building in Oakland, while Warren gave himself up inside a police station in San Francisco.

The two men were charged with first-degree murder Sunday. Lathem and Warren were being held without bail after Warren's attorney, Assistant Public Defender Courtney Smallwood asked the judge to set bond for both men. Judge Adam D. Bourgeois Jr. denied Smallwood's request for bond. Lathem's attorney, Barry Sheppard, also gave the judge documents from friends and family attesting to his client's character and accomplishments, which the judge appeared to frown upon.

"The court has read his professional and academic achievements," Bourgeois said Sunday. "Some of the finest in the world, right? It has nothing to do with this, though. The heinous facts speak for themselves."

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