Citing recent revelations in the investigation into a failed sting operation against Mexican drug cartels, the House’s lead investigator served Attorney General Eric Holder with a subpoena on Wednesday, requesting a range of documents related to the cross-border law enforcement effort.

“Top Justice Department officials, including Attorney General Holder, know more about Operation Fast and Furious than they have publicly acknowledged,” Darrell Issa, chairman of the House Oversight and Government Reform Committee said in a statement.

Fast and Furious was an operation conducted by the Bureau of Alcohol, Tobacco, Firearms and Explosives. An attempt to gather information on cartel weapons smuggling, the operation allowed 2,000 guns to pass into Mexico, where many disappeared into cartels’ hands. More than a thousand remain remain unaccounted for. Just last week, 100 Fast and Furious guns were found in the home of a cartel enforcer.

“The documents this subpoena demands will provide answers to questions that Justice officials have tried to avoid since this investigation began eight months ago,” Issa added. “It’s time we know the whole truth.”

The subpoena requests internal communications within the Justice Department, as well as communications with White House, the ATF, FBI, DEA, the Mexican government, and a gun store known to have supplied many of the weapons used in the Fast and Furious operation.

The most recent push by Issa and others in Congress was spurred by news that Holder knew about Fast and Furious nearly a year earlier than he had previously admitted. In May of this year, he told the House Judiciary Committee that he had “probably heard about Fast and Furious for the first time over the last few weeks.”

But Justice Department memos recently released by the Oversight Committee reveal that top DOJ officials briefed Holder nearly a year before the hearing, and offered some details on the workings of the investigation. The apparent discrepancy has pushed the scandal back into the headlines, and reinvigorated congressional investigators.

For his part, Holder has maintained that his remarks before the Judiciary Committee were “truthful and accurate.” He claimed that he was simply referring to knowledge of the gunwalking tactics used in the Fast and Furious operation, not knowledge of the operation itself.