CHICAGO -- Chicago police said they have an idea of the whereabouts of a Northwestern University professor and a University of Oxford employee reports CBS Chicago., and a manhunt is intensifying,
Cook County court records show that on Monday a judge issued first-degree murder warrant for 42-year-old Wyndham Lathem, an associate professor of microbiology and immunology at Northwestern, and 56-year-old Andrew Warren, a senior treasury assistant at the University of Oxford's Somerville College in England.
Chicago Police spokesman Anthony Guglielmi said Thursday that investigators believe they know where Lathem and Warren are or are heading, but he declined to elaborate.
"The search has intensified and has narrowed," he said.
A judge issued the warrant four days after Trenton James Cornell-Duranleau was found stabbed to death inside an apartment where Lathem lives in Chicago's River North neighborhood. Guglielmi said surveillance video shows the two men leaving the building the night of the slaying.
CBS News' Jericka Duncan reports investigators believe the two may have fled the state and U.S. Marshals are aiding in the search. Both of their passports have been flagged and Warren's visa has been restricted, which bars him from leaving the country, Duncan reports.
The men were last seen driving a gray Hyundai sedan.
Latham and the vicim knew each other, Duncan reports, but investigators haven't clarified how. CBS Chicago reports the victim and suspect were friends on Facebook. Investigators have not detailed a possible motive.
Former co-workers described the victim to CBS Chicago as a kind and energetic person, as well as a skilled hair stylist.
Charlotte Cornell, the mother of the victim, said Thursday she doesn't know the two men police are seeking, and she asked for privacy as relatives grieve.
Cornell issued a statement to The Associated Press saying: "Our Family is deeply saddened by the death of our son. It is our hope that the person or persons responsible for his death are brought to justice. We are asking that you allow our family to process and grieve this tragedy privately. We are asking all media outlets to not contact our family, friends or associates. When we have had sufficient time to mourn our child's passing, we will release a more in depth statement if we believe it is appropriate to do so."
In a brief telephone interview, Cornell said the family in Michigan -- where Trenton Cornell-Duranleau was born and raised before moving to Chicago -- doesn't know the suspects. She declined to say whether she or other family members had ever heard of them before her son was killed because the two suspects "are at large and there's an ongoing investigation."
She said she hoped her written statement would provide some respite for relatives who have been inundated with calls from reporters around the world.
"Maybe this (statement) can calm things down for my kids, our parents," she said. "We are asking that we have a little space during this time."