The intelligence reports at the center of the Susan Rice unmasking controversy were detailed, and almost resembled a private investigator’s file, according to a Republican congressman familiar with the documents.

"This is information about their everyday lives," Rep. Peter King of New York, a member of the House Intelligence committee said. "Sort of like in a divorce case where lawyers are hired, investigators are hired just to find out what the other person is doing from morning until night and then you try to piece it together later on.”

On the House Intelligence Committee, only the Republican chairman, Devin Nunes of California, and the ranking Democrat Adam Schiff, also of California, have personally reviewed the intelligence reports. Some members were given broad outlines.

Nunes has consistently stated that the files caused him deep concern because the unmasking went beyond the former national security adviser Mike Flynn, and the information was not related to Moscow.

Schiff said in a statement, “I cannot comment on the content of these materials or any other classified documents, and nothing should be inferred from the fact that I am treating classified materials the way they should be treated - by refusing to comment on them. Only the Administration has the power to declassify the information and make it available to the public."

Former National Security Adviser Rice is under scrutiny after allegations she sought to unmask the identities of Trump associates caught up in surveillance - such as phone calls between foreign intelligence targets. Rice denies ever having sought such information for political purposes and has defended her requests as routine.

But the most recent government data shows that unmasking or identifying Americans happens in a limited number of cases. The Office for the Director of National Intelligence, which oversees the 17 intelligence agencies, said "...in 2015, NSA disseminated 4,290 FAA Section 702 intelligence reports that included U.S. person information. Of those 4,290 reports, the U.S. person information was masked in 3,168 reports and unmasked in 1,122 reports."  

The report said "NSA is allowed to unmask the identity for the specific requesting recipient only under certain conditions and where specific additional controls are in place" and those conditions were met for "654 U.S. person identities" in 2015.

That means Americans were identified in 26 percent of the cases, or roughly one in four intelligence reports.

During his March 20 testimony before the House Intelligence Committee, NSA director Admiral Mike Rogers said only 20 individuals within the agency are authorized to approve those requests.

“They receive specific training, there are specific controls put in place in terms of our ability to disseminate information out of the databases associated with U.S. persons,” Rogers said at the time. What it appears to suggest is that the NSA itself agreed that the instances in which Rice requested unmasking warranted that action.

FBI Director James Comey was less direct. "I don't know for sure. As I sit here, surely more, given the nature of the FBI's work," he testified.

"It would be nice to know the universe of people who have the power to unmask a U.S. citizen's name," South Carolina Republican congressman Trey Gowdy pressed. "Because that might provide something of a roadmap to investigate who might've actually disseminated a masked U.S. citizen's name."

Rice told NBC News’ Andrea Mitchell that the reports were requested by the Obama administration, which announced a probe into the Russian election hacking in early December. Two months earlier in October, before the election, the Office of the Director of National Intelligence and the Homeland Security Department put out a joint statement about Moscow's interference.

Rice told Mitchell, "Fulfilling the president's request for such a report, they went back and scrubbed more reports. They began to provide more such reports to American officials, including myself."

Given the late fall timeline, it is not clear the intelligence reports Rice discussed during the NBC interview, are the same files reviewed by Nunes and Schiff.

Speaking to Fox News Wednesday, President Trump said he believed the former national security adviser may have committed a crime when she sought the identities of the Trump team members. The allegation was first reported by the New York Times.

While not commenting on the individual case, a former senior intelligence official explained the request must be approved by the NSA. Rice would have understood that there is an extensive government paper trail, that can be audited within the NSA, that shows who requested the unmasking, on what basis, and whether it was granted. This raises more questions about Rice, her motivation and whether it was authorized higher up, offering cover. 

If approved, the former senior intelligence official said, only the requester, in this case Rice, would receive the information. Based on Fox News’ reporting, the information was shared beyond Rice, but it is not clear if those who received it had a “need to know.” 

A spokeswoman for Rice, Erin Pelton, said in an email to the New York Times on Wednesday, “I’m not going to dignify the president’s ludicrous charge with a comment.”  Pelton works for Mercury LLC, a crisis management firm. 

At the height of the 2012 Benghazi terrorist attack fallout, and questions about whether Rice and a former senior intelligence official had misled Congress about the role of an internet video in the deaths of four Americans, Mercury LLC was also tasked with handling the Fox News media inquiries.

Catherine Herridge is an award-winning Chief Intelligence correspondent for FOX News Channel (FNC) based in Washington, D.C. She covers intelligence, the Justice Department and the Department of Homeland Security. Herridge joined FNC in 1996 as a London-based correspondent.

Pamela K. Browne is Senior Executive Producer at the FOX News Channel (FNC) and is Director of Long-Form Series and Specials. Her journalism has been recognized with several awards. Browne first joined FOX in 1997 to launch the news magazine “Fox Files” and later, “War Stories.”