US president Donald Trump has ordered the FBI to reopen Supreme Court nominee Brett Kavanaugh’s background investigation after several women accused him of sexual misconduct.

The Senate Judiciary Committee requested that the White House ask the FBI to conduct the supplemental investigation, which will be “limited to current credible allegations” and must be done by October 5.

Here, we take a look at what a reopened FBI investigation would and would not do:

President Donald Trump President Donald Trump has ordered the FBI to reopen a background investigation in Mr Kavanaugh (AP Photo/Alex Brandon)

What is the FBI’s role?

The FBI conducts background checks for federal nominees but the agency does not make judgments on the credibility or significance of allegations.

Investigators compile information about the nominee’s past and then provide findings to the agency that requested the background check — in this case, the White House.

The information would then be added to the nominee’s background file, which is available to senators.

Typically, background investigations do not go back decades, as will be needed in Mr Kavanaugh’s case because the allegations are about things said to have happened during his teenage years.

Could the FBI investigation bring clarity to what happened?

Perhaps. The FBI has wide discretion in determining the scope of the investigation.

The Senate Judiciary Committee has questioned Mr Kavanaugh and one of his accusers, Christine Blasey Ford, and other potential witnesses have submitted sworn statements.

But FBI agents could interview the other accusers and witnesses and gather additional evidence or details.

Mr Kavanaugh’s high school friend, Mark Judge, who Ms Ford says was in the room when a drunken Mr Kavanaugh sexually assaulted her, said on Friday that he would cooperate with any law enforcement agency that would “confidentially investigate” sexual misconduct allegations against him and Mr Kavanaugh.

Both men have vehemently denied any allegation of misconduct.

A lawyer for PJ Smyth, another person whom Ms Ford said was in the house when she was attacked, said his client was “happy to cooperate fully with this FBI investigation”.

Christine Blasey Ford Christine Blasey Ford testifies before the Senate Judiciary Committee (AP Photo/Andrew Harnik, Pool)

Can an investigation be done in a week?

Experts say the work can be done in a matter of days in most circumstances.

Ron Hosko, a former FBI assistant director, said background investigations done by the bureau typically have short turnaround times because the requesting agency needs the information quickly in order to make a decision on the nominee.

The FBI cannot force someone to talk to them as part of the process.

What does Mr Kavanaugh say on the investigation?

Mr Kavanaugh would not answer directly when he was asked on Thursday if he would agree to an FBI investigation, but said he would do whatever the Judiciary Committee wanted.

In a statement released by the White House on Friday, M Kavanaugh said he was interviewed by the FBI throughout the selection process and participated in several background calls with the Senate.

“I’ve done everything they have requested and will continue to cooperate,” he said.