Why is Hillary Clinton being quizzed again over Benghazi?

The attacks resulted in the deaths of the ambassador Chris Stevens and three other Americans: Sean Smith; Glen Doherty; and Tyrone Woods. The current congressional inquiry into the raids – and America’s preparedness for them – is the eighth. And Thursday’s session will mark the second time Hillary Clinton has been called before Congress to testify.

Previous inquiries have found that the security arrangements were inadequate and requests for reinforcements were ignored. While Clinton has previously said that the details did not cross her desk, she has taken responsibility for the lack of security at the mission.

Republicans have claimed that a muddled White House narrative in the immediate aftermath was evidence of an attempted cover up. But previous investigations have not supported those theories.

How much is left to uncover depends on who one asks.

Clinton supporters – and even some of her political opponents – say this latest session is simply a political attack on the frontrunner for the Democratic presidential nomination.

A week ago, the Republican congressman Richard Hanna told the New York radio station WIBX 950: “This may not be politically correct, but I think that there was a big part of this investigation that was designed to go after people and an individual, Hillary Clinton.”

Hanna referred to comments made by the House majority leader Kevin McCarthy, who in an appearance on Fox News’ Hannity programme last month, linked Clinton’s sliding numbers with the formation of the committee.

“What are her numbers today? Her numbers are dropping. Why? Because she’s untrustable,” he said.

And they are not the only ones.

A former staff member of the committee claimed this month that he was fired for trying to conduct a non-partisan investigation, rather than one that focused on Clinton.

On the other hand, the Republican chairman of the committee Trey Gowdy has insisted that it is covering new ground: “This committee has interviewed 41 witnesses no other committee interviewed. Seven were eyewitnesses to the attacks.

“We have reviewed 50,000 pages of documents never before given to Congress – including the emails of top State Department personnel.

“And, for the first time, State is committed to finally providing all Ambassador Stevens’ emails by week’s end”, he wrote in a USA Today article.

Gowdy added: “Secretary Clinton was in charge at all times relevant to our inquiry, so of course we need her public record and testimony.

“But she is one witness. Her emails make up five per cent of what the committee has.”

Clinton supporters, however, have dismissed that, saying that many of the other interviews have been with people closely associated with her.

The committee’s chair has clearly been irritated by the suggestion that he is playing a political game – particularly when it has come from his own side. On CBS’ Face the Nation programme on Sunday, Mr Gowdy had two words of advice for such colleagues: “Shut up.”

After a lengthy period on the back foot as questions abounded about her use of a private email server for official business, Clinton’s supporters are hoping she could seize the initiative once again with a strong performance on Thursday.

Amid a heated debate over whether the inquiry is a naked political attack or a genuine attempt to finally weed out the truth, she has perhaps as much to gain as she has to lose.