The missing plague-infected mice may never be found, according to federal officials.

The mice were unaccounted-for at the Public Health Research Institute, which is on the campus of the University of Medicine and Dentistry of New Jersey and conducts bioterrorism research for the federal government.

Federal official said the mice may never be accounted for. Among other things, the rodents may have been stolen, eaten by other lab animals or just misplaced in a paperwork error.

If the mice got outside the lab, they would have already died from the disease, state Health Commissioner Fred Jacobs said.

Lab Employees Interrogated

The possibility of theft prompted the institute to interrogate two dozen of its employees and conduct lie detector tests, The Star-Ledger of Newark reported Thursday.

The FBI said it was investigating. The Centers for Disease Control and Preventionis also investigating, the newspaper reported.

University officials did not immediately return a call seeking comment Thursday morning.

The mice were injected as part of an inoculation and vaccination experiment, investigators said.

Can Transform Into Pneumonic Plague

Health officials say 10 to 20 people in the United States contract plague each year, usually through infected fleas or rodents. It can be treated with antibiotics, but about one in seven U.S. cases is fatal. Bubonic plague is not contagious, but left untreated it can transform into pneumonic plague, which can be spread from person to person.

The incident came as federal authorities investigate possible corruption in the school's finances. The FBI is reviewing political donations and millions of dollars in no-bid contracts awarded to politically connected firms.