Police in the US have ruled out a love triangle between an Oxford University employee, a US professor, and a 26-year-old hairdresser, whose murder the pair have been charged with, instead saying there was a "dark and disturbing" motive behind the death.
Somerville College's Andrew Warren, 56, and Professor Wyndham Lathem, 42, are accused of killing Trenton Cornell-Duranleau in the academic's apartment in Chicago.
Mr Cornell-Duranleau, who police say was in a personal relationship with Lathem, was found with more than 40 stab wounds on July 27.
However, Chicago Police's Commander Brendan Deenihan said there was a "dark and disturbing" motive behind the death.
Mr Deenihan said: "It was not domestic in nature like a husband-wife, or boyfriend-boyfriend, or love triangle - that was not the motive.
"It was a little bit more dark and disturbing as far as I'm concerned."
Chicago Police said Warren and Lathem had both been charged with first degree murder after they were returned to the city from California, where they handed themselves in following a nationwide manhunt, during which they travelled across the country in a car, police said.
Mr Deenihan continued that Lathem and Warren met on the internet, and the professor collected the Briton from Chicago's O'Hare airport just days before the body was found.
Police found Mr Cornell-Duranleau after a doorman at the block received an anonymous call, later found to be from Lathem, that a crime may have been committed there, Mr Deenihan added.
The charges came after a post-mortem examination found the victim had methamphetamines in his system.
Witnesses later told police they had heard a fight and screaming at around 5am and detectives found two knives at the scene, one of which had been broken.
Warren, who says on Facebook that he lives in Swindon, Wiltshire, was suspended from his job as senior treasury assistant after Mr Cornell-Duranleau's body was discovered.
Microbiologist Lathem, who has since been sacked by Northwestern University, plans to plead not guilty, according to his lawyer.