A Chicago Police spokesman on Thursday said authorities are narrowing their search “by the hour” for a Northwestern University professor and an Oxford University employee believed to have been involved in a fatal stabbing in the River North neighborhood.

“We know where they might be, and we have more information coming in,” Anthony Guglielmi said about Wyndham Lathem and Andrew Warren.

“We want to facilitate a safe surrender.”

Meanwhile, Guglielmi provided more details from the night 26-year-old Trenton H. James Cornell-Duranleau was killed in Lathem’s luxe apartment building on July 27.

At 8:30 p.m., an attendant working the front desk received a cryptic phone call in which a male caller said, “There may have been a crime committed in Room 1004. You need to check it out.”

The attendant called the room, and when he got no response, called police. Officers entered the apartment with the building manager, and discovered a “gruesome scene,” Guglielmi said.

On Monday a Cook County judge issued arrest warrants for Lathem, 42, and Warren, 56, a payroll assistant at Oxford University’s Somerville College in England.

Guglielmi said detectives believe the pair have fled Illinois, but their passports have been flagged by the State Department, and the U.S. Marshal Service has joined the search.

“The search for them will only intensify,” Guglielmi said. “They should do the right thing and turn themselves in to any police station. It’s only a matter of time.”

Police had been looking for Lathem soon after Cornell-Duranleau was found dead inside the professor’s flat in the Grand Plaza Apartments, 540 N. State, around, when police responded to a request for a wellness check. Lathem is listed as the registered owner of the apartment, which sits just over a mile from his office in Northwestern’s Feinberg School of Medicine, Guglielmi said.

Lathem and Cornell-Duranleau appear to have lived together at the River North apartment, Guglielmi said. The connection to Warren, who is an employee of a college within the Oxford University system, is not known.

The Cook County Medical Examiner’s Office found that Cornell-Duranleau died of multiple stab wounds and ruled the death a homicide.

A notice emailed last week to Grand Plaza residents by building managers after Cornell-Duranleau’s body was discovered said that Chicago Police were investigating “a variety of motives, including a possible domestic incident.”

The murder is the first in the River North police beat that covers the 500 block of North State since at least 2001, according to the Chicago Police crime database.

Lathem is an associate professor of microbiology and immunology, and primarily works as a researcher and seldom interacted with students. Lathem was placed on administrative leave and is barred from campus, Northwestern spokesman Alan Cubbage said.

Cornell-Duranleau had graduated from cosmetology school in Michigan, and had moved to Chicago fairly recently. His address was a small, worn-looking apartment building in the Heart of Chicago neighborhood, and neighbors said he was quiet and kept to himself.

“I don’t know much about him, but what I’ve heard about what happened, shouldn’t happen to anybody,” said a neighbor who had lived in the building for about a year. “He deserves justice. I’m glad they think they know who did it.”

In an obituary posted on her Facebook page, his mother, Mischelle Duranleau, said he was born in the small town of Lennon, Michigan, and loved animals, music, cars and video games. His biological mother died when he was young, and he was adopted by Duranleau and raised among a large family of adopted siblings.

“His enthusiasm for life was infectious. Trenton was a caregiver and loved to help others,” Duranleau wrote.

His funeral will be held on Aug. 12 in Lennon. A brief death notice in the local newspaper noted that Cornell-Duranleau “died suddenly” on July 27.

University officials said Wednesday that Lathem has been placed on administrative leave and banned from entering Northwestern campuses. Lathem had worked at Northwestern since 2007.

“There is no indication of any risk to the Northwestern community from this individual at this time,” Cubbage said in an emailed statement.

By Wednesday morning, the school had removed his profile page and numerous press releases about his research.

The website for Oxford’s Somerville College listed Warren as a “senior treasury assistant.” A college spokesman said the school was not aware of the investigation, but that officials there would “liaise” with investigators.