The recently released State Department inspector general report, which found Hillary Clinton broke government rules with her personal email use, increases "the likelihood and pressure" for the Justice Department to pursue criminal charges, an intelligence source familiar with the FBI investigation told Fox News.

"It is very harmful to her and increases the likelihood and pressure on DOJ to indict," said the source, who was not authorized to speak on the record. "[The IG report] is not evidence in itself, but it clears up confusion [about] Department of State rules and makes the IG a witness, and the people they interviewed, to her computer antics being done without permission."  

The ongoing FBI criminal probe -- investigating Clinton's emails practices as secretary of state -- is focused on whether the more than 2,100 classified emails discovered on her server constitute a violation of federal code, including the Espionage Act’s 18 USC 793, known as the "gross negligence" statute. FBI Director James Comey plans to make a recommendation based on the evidence, and if the findings merit criminal charges, the decision to prosecute ultimately rests with Attorney General Loretta Lynch. 

The 83-page inspector general's report, released last week, concluded that Clinton and her team consistently broke government rules for email and record-keeping. The decision to use a personal, unsecured server exclusively for government business had the effect of moving classified information outside secure government channels.

Fox News first reported in November 2015 that another statute, 18 USC 1001, also known as the "false statements statute," was under FBI consideration. This section pertains to "materially false" statements given either in writing, orally or through a third party to a federal officer. Each felony violation is subject to five years in prison. 

"[The] report will be useful as rebuttal, potential evidence in 18 USC 1001 charges and establishing aspects of 18 USC 793," the source said. 

Asked about the conflict between the IG report's findings and Clinton's continued insistence that her practices were in line with her predecessors’, the source noted the candidate’s press releases and media interviews on the issue “don’t count,” legally speaking, in determining whether false statements were made: “They can be used to show a pattern of deceit but not the basis of a charge."

Meanwhile, an investigator with the conservative watchdog group Judicial Watch said Wednesday they are considering whether to go back to a federal judge regarding a deposition last week with longtime Clinton aide Cheryl Mills.

The group is considering whether to try to compel Mills to answer questions about Clinton IT special Bryan Paligano, who managed the Clinton server.

Pagliano, a central figure in the FBI probe who was granted immunity in a deal with the Justice Department late last year, has been described to Fox News as a "devastating witness" because he has provided information allowing investigators to knit together the emails with other evidence, including images of Clinton on the road as secretary of state. 

The cross-referencing of evidence could help investigators pinpoint potential gaps in the email record.

Yet seven lawyers -- four representing the Justice and State Departments, along with Mills’ personal attorneys -- objected more than 200 times during Friday's five-hour deposition, effectively blocking Mills’ responses to questions about Pagliano’s role. 

"The details concerning Mr. Pagliano's employment status -- whether he was an agent of the Clintons, whether he was an employee of the State Department, the details about what that shift was and how it was conducted, whom Mr. Pagliano reported to in the State Department -- those are all unanswered questions by Ms. Mills," Judicial Watch Director of Research and Investigations Chris Farrell said.

"We may have to go back to the court to have the judge compel Ms. Mills to answer those questions."

While Clinton did not cooperate with the State Department inspector general and his investigators, she has  maintained that she is  willing to talk with the FBI – although she told MSNBC on Tuesday the bureau has not yet scheduled an interview.

In a weekend memo to Clinton donors, campaign chairman John Podesta said Clinton acknowledges the server was a “mistake,” and “what she thought would be a convenient way to communicate with family, friends and colleagues by using one email account…has turned out to be anything but convenient.”

Podesta said the report confirms Clinton’s email account was well-known by many State Department officials and there is no evidence of a “breach of her email server.” 

A congressional source briefed on the IG report earlier told Fox that hacking was outside the scope of State Department investigators and they reached no conclusions about a compromise.

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.”