To quote Wilford Brimley in Absence of Malice: “Wonderful thing, subpoenas.” Don’t set your DVR just yet, as this subpoena will serve as an “invitation” to a closed-door but transcribed hearing. Still, the move to collar longtime Clintonista Sid Blumenthal qualifies as a major development for the Benghazi Select Committee investigation:

Representative Trey Gowdy of South Carolina, a Republican who is leading the congressional committee investigating the 2012 attacks in Benghazi, Libya, plans to subpoena Mr. Blumenthal, 66, for a private transcribed interview.

Mr. Gowdy’s chief interest, according to people briefed on the inquiry, is a series of memos that Mr. Blumenthal — who was not an employee of the State Department — wrote to Mrs. Clinton about events unfolding in Libya before and after the death of Col. Muammar el-Qaddafi. According to emails obtained by The New York Times, Mrs. Clinton, who was secretary of state at the time, took Mr. Blumenthal’s advice seriously, forwarding his memos to senior diplomatic officials in Libya and Washington and at times asking them to respond. Mrs. Clinton continued to pass around his memos even after other senior diplomats concluded that Mr. Blumenthal’s assessments were often unreliable.

But an examination by The Times suggests that Mr. Blumenthal’s involvement was more wide-ranging and more complicated than previously known, embodying the blurry lines between business, politics and philanthropy that have enriched and vexed the Clintons and their inner circle for years.

Blumenthal will make a key witness on at least two different threads of the investigation. First, he can provide testimony on Hillary Clinton’s use of the private e-mail server, as previously hacked e-mails show that he used that system to bypass the State Department and communication directly with Hillary, despite Barack Obama’s demand that Blumenthal be kept out of the state department. Testimony in that regard will be necessarily limited to his own experience with the e-mail system, though, and probably won’t get Gowdy all that much farther than where the committee has already gone on that subject.

Much more importantly, Blumenthal may shed light on Clinton’s disastrous Libya policy. She and Obama turned it from a dictatorship with some vested interest in fighting al-Qaeda and its affiliates into a failed state where terrorist networks now operate openly. Blumenthal appears to be a key figure in that policy development, and it now appears that he had financial interests in play at the time:

Much of the Libya intelligence that Mr. Blumenthal passed on to Mrs. Clinton appears to have come from a group of business associates he was advising as they sought to win contracts from the Libyan transitional government. The venture, which was ultimately unsuccessful, involved other Clinton friends, a private military contractor and one former C.I.A. spy seeking to get in on the ground floor of the new Libyan economy. …

It is not clear whether Mrs. Clinton or the State Department knew of Mr. Blumenthal’s interest in pursuing business in Libya; a State Department spokesman declined to say. Many aspects of Mr. Blumenthal’s involvement in the planned Libyan venture remain unclear.

In other words, there’s nothing much more here than with other players at the Clinton Foundation, including Hillary and Bill. Everyone at the foundation seemed interested in finding ways to enrich themselves while fronting for the organization, including Blumenthal, who was working there at the same time as he consulted for Media Matters and American Bridge, the PAC that’s pushing Hillary for President. His job: “message guidance” and research.

Gowdy’s interest will certainly be in potential conflicts of interest. The NY Times has got some intriguing nuggets from the e-mails already:

In January 2012, Mr. Blumenthal wrote to Mrs. Clinton about challenges facing Libya’s new government. In the memo, Mr. Blumenthal said that Libya’s prime minister was bringing in new economic advisers, and that a businessman, Najib Obeida, was among “the most influential of this group.” At the time, Mr. Obeida was a potential business partner for a group of contractors whom Mr. Blumenthal was advising. Mrs. Clinton instructed Mr. Sullivan to ask for a response from senior State Department officials including Mr. Cretz, then the ambassador to Libya.

Before the US began its attack on Moammar Qaddafi, Blumenthal suggested that Clinton should get the rebels some training:

In April 2011, Mr. Blumenthal sent Mrs. Clinton a memo about the rebel forces fighting the regime of Col. Muammar el-Qaddafi. The rebels, Mr. Blumenthal wrote, were considering hiring security contractors to train their forces. Mrs. Clinton forwarded the memo to her aide, Jake Sullivan, and said that the idea should be considered.

How much of Hillary Clinton’s Libya policy got driven by the financial interests of Sidney Blumenthal? How deep did Blumenthal’s private amateur intel service go, and who were its targets? Gowdy has plenty of material for his subpoenas, and the transcript of that chat will make for very interesting reading. As Ben Mathis-Lilley wrote at Slate yesterday about Blumenthal and the Clinton Foundation: