Senior law enforcement officials said that a late-night seizure on Monday of boxes of material from the North Carolina home of Paula Broadwell, a Petraeus biographer whose affair with him led to his resignation last week, marks a renewed focus by investigators on sensitive material found in her possession.

“The issue of national security is still on the table,” one U.S. law enforcement official said. Both Petraeus and Broadwell have denied to investigators that he was the source of any classified information, officials said…

Law enforcement officials offered conflicting accounts of the significance of the FBI’s seizure of materials from Broadwell’s home. Officials said Broadwell provided access to the residence, which the FBI requested on Sunday, and turned over computers, files and other material. She was not present when the search occurred over several hours Monday night.

A second U.S. law enforcement official acknowledged that investigators remain focused on determining whether classified material was compromised but that more serious threats were ruled out. One official called the search a “clean-up effort” in the wake of congressional questions and publicity to ensure that the FBI had not missed any classified documents in its initial search or the significance of items already examined and discussed with her…

The ongoing effort is now aimed mainly at Broadwell. It “is now about the source of documents on her computer,” the official said. “At this point, there is no evidence to support that [Petraeus] was the source.” The official added that it would be a “little breathless to describe it as a national security investigation.”