Reality check verdict: The US president has the power to both dismiss and appoint the director of the FBI.

US President Donald Trump sacked James Comey, director of the FBI, on 9 May, with immediate effect. Mr Trump said he had acted on the recommendation of senior figures at the Justice Department, criticising Mr Comey's handling of the investigation over Hillary Clinton's emails.

Mr Comey was sworn in as the seventh FBI director in September 2013, under the Obama administration.

He was in his fourth year of a potential 10-year term, heading the organisation within the Justice Department with a broad array of powers to investigate domestic crime and to gather intelligence.

How can a president simply fire the head of the FBI?

According to federal law, the president has authority to both appoint and dismiss the director of the FBI, as well as other senior officials in the Justice Department, but the nominee has to pass hearings and be confirmed by a simple majority vote in the Senate.

Only one FBI director has been removed by the President in the bureau's 100-plus-year history. That man was William Sessions, who was fired by President Bill Clinton in 1993.

As president, Mr Trump has used his power to remove senior officials in the Justice Department before. He fired the acting attorney general, Sally Yates, at the end of January this year.

So what happens now?

The White House says the search for the next director has already begun.

Before his removal from office, Mr Comey was in charge of investigations into alleged Russian interference during the 2016 presidential election. During a Senate hearing on 20 March 2017, Mr Comey acknowledged that potential links between Trump's associates and Russia were also under review.

There's no reason why the investigation would stop, but with Mr Comey gone, Democrats in Congress are demanding that a special prosecutor be appointed to oversee the investigation into Russian involvement in the election.

Deconstructing Comey's testimony on Clinton emails