The special counsel investigation run by Robert Mueller has cost taxpayers more in four months than what the investigation into the Benghazi terrorist attack cost in over two years.

Mueller and his team spent $6.7 million between May and September, according to a new report released by the Department of Justice.

The figure includes $3.2 million in direct costs and $3.5 million in DOJ components that supported the special counsel's office. The costs include $1.7 million for salaries and benefits, $223,643 for travel, $362,550 for rent, $111,245 for IT services, and $3,554 in "miscellaneous" costs.

The House Select Committee on Benghazi cost $6.7 million over the course of more than two years, according to the Washington Post.

In 2015, Democrats complained that the Republican-led congressional investigation into the terrorist attack on the U.S. consulate in Benghazi, Libya, that killed four Americans was a waste of taxpayer dollars.

Democratic members of the select committee kept a spending tracker, which at the time showed expenses less than what the federal government had spent researching "origami condoms" and obese lesbians.

The special counsel was appointed to investigate "the Russian government's effort to interfere into the 2016 presidential election" and "any links/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump." Since then, Mueller has expanded his mandate into Trump's business dealings going back decades and to activity during the presidential transition.

The special counsel investigation has yet to reveal evidence of collusion. The investigation has resulted in former national security adviser Michael Flynn pleading guilty to making false statements to the FBI regarding conversations after the election with the Russian ambassador to the United States.

Former Trump campaign chairman Paul Manafort was indicted on charges related to his foreign lobbying and money laundering, unrelated to the Trump campaign. George Papadopoulos, a foreign policy adviser to the campaign, also pleaded guilty to making false statements to the FBI, over his attempts to court a professor in London who promised to introduce him to Vladimir Putin's "niece" who had "dirt" on Hillary Clinton.