Federal agents last week raided a Medicare claims processing center in Marion, Ill., owned by Blue Cross and Blue Shield of Illinois.
The center is one of six in the state owned by the Illinois Blues' parent, Chicago-based Health Care Services Corp., the Medicare administrator in Illinois.
"We do not know the government's purpose for obtaining these records," said HCSC spokesman John Gleason.
The Illinois Blues is a Medicare fiscal intermediary, handling 25 million claims annually.
Ten agents from the FBI and HHS' inspector general's office spent five hours Nov. 6 taking provider-certification documents, Gleason said.
A warrant was issued by the agents on behalf of the U.S. attorney's office in Fairview Heights, Ill. The U.S. attorney's office wouldn't comment on the raid.