An associate professor at Northwestern University and an employee of England's University of Oxford are wanted in the killing of a 30-year-old man found inside the professor's Chicago apartment.
Chicago police issued first-degree murder arrest warrants on Wednesday for Wyndham Lathem, associate professor of microbiology and immunology at Northwestern University, and Andrew Warren, who works for Oxford.
Police told CNN they could not elaborate on any possible relationship between the victim and the two suspects.
Lathem, 42, and Warren, 56, are suspected of stabbing 30-year-old Trenton Cornell-Duranleau, a Chicago-area cosmetologist, inside Lathem's Grand Plaza Apartment in the River North Neighborhood, police said.
Police on Thursday told CNN they believe the suspects have fled the area.
"We do have an idea of their whereabouts and efforts to locate them are only intensifying from here on in," said Chicago Police in an email to CNN. "Our primary focus is to facilitate a safe surrender."
Lathem's passport and Warren's travel visa have been restricted.
Officers found Cornell-Duranleau on July 27.
"There's shock, there's no doubt about it. You know, this place is very safe," Grand Plaza Apartments resident Richard Aili told CNN affiliate WLS-TV. "I've been here 14 years and I've never heard of problems such as that."
Chicago Police spokesman Anthony Guglielmi tweeted a plea for the two to turn themselves in.
"Our search will only intensify," he said. " Prof. Lath(e)m & Mr. Warren, do the right thing & turn yourself in to any police dept."
According to WLS, investigators determined that Warren had recently come to Chicago from England, but didn't know whether he knew the victim.
Northwestern released a statement, saying Lathem "has been placed on administrative leave and banned from entering the Northwestern University campuses."
The statement added: "This is now a criminal matter under investigation by the appropriate authorities, and Northwestern University is cooperating in that investigation."
Lathem joined the Northwestern faculty in 2007 and researched bacteria that cause disease in humans, particularly lung infections, according to his university biography page, which has since been removed.
CNN reached out Thursday to the University of Oxford, but received no immediate comment.