Lathem is a well-published microbiologist known for his work on the plague of the Middle Ages known as the Black Death.



Late last month, an anonymous call brought police to Lathem's Chicago apartment in the 500 block of North State Street where they found the body of 26-year-old Trenton Cornell-Duranleau, who had been stabbed and slashed to death in the bedroom, authorities said.



Arrest warrants were issued for Lathem and an acquaintance, Andy Warren, 56, an employee of Oxford University who had traveled to the United States for the first time just days before Cornell-Duranleau was found July 27.



The case attracted international attention as the men evaded police for more than a week until their surrender in California last Friday. Lathem surrendered in Oakland, while Warren turned himself in at a police station across the bay in San Francisco.



Lathem, wearing a dark red jail suit, appeared briefly in court Monday. He nodded his head and mouthed some words at five supporters in the courtroom. One of his friends blew him a kiss and he appeared to say "thank you" back.



His attorney, Kenneth Wine, asked that Lathem not be questioned by law enforcement without an attorney present. He also asked the judge to ensure that Lathem receive contact lens solution, saying his client has been unable to clean his contact lenses since he's been in custody. Judge Stuart Hing agreed.



Lathem has been under "intensive observation" — formerly known as suicide watch — at Santa Rita Jail in Alameda County. Warren is being held in San Francisco County and has yet to appear in court. A hearing is scheduled for Friday.



Lathem has waived his extradition rights, and Warren is expected to do the same, authorities said. They could return to Chicago in the next few weeks.



As Lathem appeared in court, Northwestern announced it had fired him because he fled police to avoid an arrest warrant. It had suspended him and banned him from its campuses after the warrants were issued. Lathem had worked for the university as an associate professor since 2007.



Lathem has conducted extensive research on Yersinia pestis, the bacteria that decimated Europe during the Middle Ages in the Black Death.



The U.S. Centers for Disease Control and Prevention regulates research using Yersinia pestis, one of 66 biological agents the center has identified as posing a severe health threat. Yersinia pestis is considered a Tier 1 agent, the riskiest class of biological substances and toxins. The Ebola and smallpox viruses are also classified as Tier 1, according to the CDC.



As part of the CDC's Federal Select Agent Program, anyone working with these substances must undergo a security risk assessment by the FBI's Criminal Justice Information Services Division.



American scientists working with these substances are routinely fingerprinted, according to William Goldman, a former academic adviser to Lathem who also studies Yersinia pestis.



"Because of the implications for biodefense, you have to pass a security clearance," said Goldman, who chairs the Department of Microbiology and Immunology at the University of North Carolina's medical school.



"We renew this every three years," he said. "I would have assumed if anything were to come up, it would come up in this country."