WASHINGTON, DC - OCTOBER 25: U.S. Attorney General Eric Holder speaks at the 18th Annual HRC National Dinner at The Walter E. Washington Convention Center on October 25, 2014 in Washington, DC. (Photo by Paul Morigi/Getty Images)

Attorney General Eric Holder criticized Rep. Darrell Issa’s (R-Calif.) years-long congressional probe into "Operation Fast and Furious" as little more than an effort to "suck up to the gun lobby," according to internal emails released Monday.

The Justice Department released nearly 65,000 pages of subpoenaed documents related to the DOJ’s botched gunrunning sting, after a federal judge overruled the Obama administration’s decision to withhold the records by invoking executive privilege. The program, which targeted Mexican gun cartels, came under scrutiny after weapons involved in the operation were connected to the killing of U.S. Border Patrol agent Brian Terry in 2010.

"Issa and his idiot cronies never gave a damn about this when all that was happening was that thousands of Mexicans were being killed with guns from our country," Holder wrote to members of his staff in April 2011, after Issa threatened to subpoena a Federal Firearms Licensee witness to testify on the investigation. “All they want to do -- in reality -- is cripple ATF and suck up to the gun lobby," he continued, referring to the Bureau of Alcohol, Tobacco, Firearms and Explosives, the branch of the Justice Department that was in charge of the gunrunning operation.

"Politics at its worst -- maybe the media will get it," Holder's email added.

Issa, who heads the House Oversight and Government Reform Committee, has accused Holder and other top Justice Department officials of refusing to disclose confidential materials in an effort to cover up knowledge of risky gun-walking activities related to the failed ATF mission.

Justice Department spokesman Brian Fallon said the sought-after documents only further confirm that neither Holder nor other top department officials knew about the tactics used in the operation until CBS News broke the story in early 2011.

"There is nothing in the materials produced today that contradicts what the Department has said in the past about this flawed operation," Fallon said in a statement Tuesday, according to The Washington Post. "Indeed the materials produced today affirm the Inspector General’s finding that the Attorney General was not made aware of the tactics involved in the Fast and Furious operation until February 2011."

A 2012 investigation by the Justice Department's Office of the Inspector General also concluded that Holder was not aware of the gunwalking strategy and cleared him of allegations of a cover-up.

Still, Issa said on Tuesday that the disclosure was evidence of Holder and President Barack Obama "illegitimately and illegally" withholding evidence from Congress. The congressman cited redactions of certain sensitive law enforcement information as cause for further investigation.