President Donald Trump on Friday ordered the FBI to reopen the background investigation on his Supreme Court nominee Brett Kavanaugh after Senate Judiciary Committee member Sen. Jeff Flake, R-Arizona, said he would only vote for Kavanaugh's recommendation to the full Senate if a new investigation was launched.

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Trump, who had initially balked at Democrats demands for a new investigation, granted the request of the committee’s chairman, Sen. Chuck Grassley, R-Iowa, that the FBI conduct an additional investigation that is “limited to current credible allegations.”

While The New York Times has reported that the inquiry would include questioning only four people, Trump said over the weekend that the FBI has "free rein" to speak with whomever they need to.

"They're going to do whatever they have to do, whatever it is they do. They'll be doing things that we have never even thought of," Trump said Saturday. Later he said he wanted the FBI to “interview whoever they deem appropriate, at their discretion."

How is an FBI background check done, will the agency be able to prove what happened in the 1980s and what will happen to the information gathered?

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Here is what will happen with the FBI’s investigation into allegations against Kavanaugh:

What does the FBI do in such an investigation? What is the agency’s role?

In a background investigation, the FBI is charged with collecting information about a person’s past. Any criminal record or problems with a credit record are noted. Agents talk with people from the person’s past and those in their lives in recent times.

Will the FBI be able to confirm the allegations against Kavanaugh after this investigation?

That is not what an FBI background check does. Background checks done by the FBI are, basically, a collection of witness statements. The agencies do not make judgments on the credibility of allegations brought against a person. The information from an FBI investigation is compiled by agents, and the findings are reported back to the agency that requested the background check. The information is given to the requesting agency – in Kavanaugh’s case it is the White House – does not include a finding on whether any allegation made before or during the investigation is true.

Who is the FBI interviewing?

According to the story from Times, the FBI has been given a list of four witnesses to interview: Mark Judge, Leland Keyser, PJ Smyth, and Deborah Ramirez. According to Dr. Christine Ford's testimony, Judge, Keyser and Smyth were at the home where Kavanaugh allegedly assaulted her. She testified that Judge was also in the room where the assault happened.

Ramirez is the second woman who publicly accused Kavanaugh of improper behavior. She claims a drunken Kavanaugh exposed himself to her at a party when the two attended Yale University.

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Judge had said he did not want to appear before a Senate committee hearing, and that he and Kavanaugh did not do what Ford claims they did. Keyser and Smyth both say they do not recall the party Ford testified about.

Can the FBI make people talk to them for the background check?

No, they can’t. A background check is not a criminal investigation. They have no means to compel anyone to talk to them.

Any restrictions on this background check?

The White House has called for a “limited” investigation, per the request of Grassley.

"The White House is not micromanaging this process," Sanders said on "Fox News Sunday." "The Senate is dictating the terms, they laid out the request. As you've heard the president say, do what you need to do, and we're out of the way and doing exactly that."

Trump said Saturday that the FBI has "free rein" over the investigation. Sen. Dianne Feinstein, D-California, in a letter to Donald McGahn, the White House counsel, and FBI Director Christopher A. Wray, asked for a copy of the White House directive sent to the FBI laying out the scope of the investigation.

“If the FBI requests any expansion beyond the initial directive, please provide the names of any additional witnesses or evidence,” Feinstein wrote in the letter.

According to a statement from Trump, "I've ordered the FBI to conduct a supplemental investigation to update Judge Kavanaugh's file. As the Senate has requested, this update must be limited in scope and completed in less than one week.”

Who will get the report?

The White House will get the report when it is complete.

When is the report due?

The FBI has been given a deadline of Oct. 5 (this Friday) to complete its investigation and report the findings to the White House.

What happens after the report is completed?

The report will go to the White House and then it would likely be shared with the Senate Judiciary Committee, though there is no legal requirement for that to happen. After that, the committee could determine that no new information was gathered that helped to settle questions they have.