Oxford University has urged an employee to hand himself in after police in Chicago said he is wanted alongside a US professor on suspicion of murdering a 26-year-old man.
Police are hunting for Somerville College senior treasury assistant Andrew Warren, 56, and Wyndham Lathem, a 42-year-old microbiology professor at Northwestern University
They repeatedly stabbed Trenton Cornell-Duranleau in Lathem's apartment before fleeing, according to Chicago Police.
An Oxford University spokesman said on Thursday the institution has been in contact with officers in the UK and is prepared to assist the US investigation.
"Andrew Warren's colleagues at Somerville College have now all been informed and are shocked to learn of the case," he added.
"Whatever the circumstances, we would urge him to contact the US authorities as soon as possible, in the best interests of everyone concerned."
Police said they believe the suspects have fled Chicago and they have placed restrictions on Warren's visa and Lathem's passport to prevent them leaving the country.
"We do have an idea of their whereabouts and efforts to locate them are only intensifying from here on in," a spokesman said.
"Our primary focus is to facilitate a safe surrender and we strongly encourage Professor Lathem and Mr Warren to do the right thing."
Officers say the victim, who lived in Chicago, was found with multiple stab wounds in the 10th floor apartment near the city centre at around 8.30pm on July 27 before being pronounced dead at the scene.
Warren, who goes by the name of Andy, is in charge of payroll and pensions at Somerville College, according to a university web page which has since been deleted.
Court files give his address as the Oxford college but he says on Facebook that he lives in Swindon, Wiltshire, and is a former cashier and driver for Stagecoach.
Mr Cornell-Duranleau, originally from Corunna, Michigan, used to work as a hair stylist, according to his Facebook profile.
Lathem is friends with the victim on Facebook but their relationship is not yet clear.
Lathem has worked at Northwestern since 2007 and specialises in the bacteria that caused the bubonic plague.
Northwestern University said he has been placed on leave and is banned from entering the campus.