House Speaker John Boehner accused the State Department Thursday of "stonewalling" the select committee charged with investigating the 2012 terror attack in Benghazi.

His office noted the link between the agency's top attorney in charge of releasing Hillary Clinton's emails, Catherine Duval, and Clinton's own attorney, David Kendall.

Duval previously served in the Internal Revenue Service and presided over the unsuccessful search for the missing emails of Lois Lerner, the former official in charge of the agency's tax-exempt unit.

Before the IRS, Duval worked at the law firm of Williams & Connolly — the same firm that presently employs Kendall.

Boehner's office pressed Secretary John Kerry to hasten the State Department's cooperation with the House Select Committee on Benghazi and their document requests, several of which have languished within the agency for months.

The State Department handed over 3,600 Benghazi-related documents to the committee Tuesday after Chairman Trey Gowdy threatened to haul Kerry before Congress if the agency continued to drag its feet.

In a letter to the South Carolina Republican Tuesday, the State Department also noted its intention to withhold a "small number" of documents that "implicate important Executive Branch institutional interests."

State officials have withered criticism of their slow response to congressional inquiries in the nearly three years since the Benghazi attack.

Despite multiple probes of the event — including an internal review by a State-appointed board — the select committee has been the first investigative body to uncover Clinton's use of a private email address and server to shield her government communications.

The Benghazi select committee was also the first congressional investigation to note the role of Sidney Blumenthal, a controversial former aide to the Clintons, in shaping the secretary's policy toward Libya.

The new findings have cast doubt on Democrats' assertions that the select committee's continued investigation is merely a "political charade" meant to damage Clinton's presidential campaign.