Now that the public knows Hillary Clinton destroyed all the emails on her secret server — her lawyer told the House Benghazi Select Committee that there's nothing left to search — a question remains: Did Clinton destroy documents that were under subpoena from Congress?

The answer is more complex than it might seem. There's no doubt Clinton withheld information that Congress demanded she turn over, and some Republicans believe the documents she destroyed were covered under a subpoena as well. But a look at the story behind the subpoena and other document requests from congressional Benghazi investigators is a tale of obstruction, delay and frustration that underscores the limits of Congress' power to investigate Benghazi. Clinton and her aides had the means to make life very difficult for Republicans trying to learn the full story of the attacks in Libya, and they did just that.

The subpoena story began on Sept. 20, 2012, nine days after the attacks. Rep. Jason Chaffetz, who was chairman of the House Oversight Committee's Subcommittee on National Security, Homeland Defense and Foreign Operations, sent a letter to then-Secretary of State Clinton asking for "all information … related to the attack on the consulate." Chaffetz specifically asked for all analyses, whether classified or unclassified, on the security situation leading up to the Benghazi attack, plus, among other things, all analyses that either supported or contradicted UN Ambassador Susan Rice's assertion that the attack was the spontaneous result of outrage over an anti-Muslim video. The short version of the letter was that Chaffetz demanded "all information" on Benghazi.

Just to be clear, the Chaffetz letter included standard language telling Clinton, "In complying with this request, you are required to produce all responsive documents that are in your possession, custody, or control, whether held by you or your past or present agents, employees, and representatives acting on your behalf." The letter went on to include this standard definition:

The term "document" refers to any written, recorded, or graphic matter of any nature whatsoever, regardless of how recorded, and whether original or copy, including, but not limited to, the following: memoranda, reports, expense reports, books, manuals, instructions, financial reports, working papers, records, notes, letters, notices, confirmations, telegrams, receipts, appraisals, pamphlets, magazines, newspapers, prospectuses, inter-office and intra-office communications, electronic mail (e-mail), contracts, cables, notations of any type of conversation, telephone call, meeting or other communication, bulletins, printed matter, computer printouts, teletypes, invoices, transcripts, diaries, analyses, returns, summaries, minutes, bills, accounts, estimates, projections, comparisons, messages, correspondence, press releases, circulars, financial statements, reviews, opinions, offers, studies and investigations, questionnaires and surveys, and work sheets (and all drafts, preliminary versions, alterations, modifications, revisions, changes, and amendments of any of the foregoing, as well as any attachments or appendices thereto), and graphic or oral records or representations of any kind (including, without limitation, photographs, charts, graphs, microfiche, microfilm, videotape, recordings and motion pictures), and electronic, mechanical and electric records or representations of any kind (including, without limitation, tapes, cassettes, disks, and recordings) and other written, printed, typed or other graphic or recorded matter of any kind or nature, however produced or reproduced, and whether preserved in writing, film, tape, disk, videotape or otherwise. A document bearing any notation not a part of the original text is to be considered a separate document. A draft or non-identical copy is a separate document within the meaning of this term.

In other words, the committee wanted everything.

The State Department, as is now well known, was slow to respond. But after months of delay, State officials told the committee they would hand over material — but only for what is called "in camera" review, meaning State retained possession of the papers at all time and no documents could leave the room in which committee investigators were allowed to view them. State agreed to bring documents to a reading room selected by the committee, where committee investigators could look them over and make handwritten notes. Over the course of months, the number of pages grew to 25,000, which State Department officials told the committee was everything related to Benghazi.

"The State Department actively told us that they were cooperating with us," says one Hill Republican with knowledge of the investigation. "They made representations that the documents in the reading room were complete and responsive."

But the committee was not given possession of the material. Each day, State officials brought the documents to the reading room, and at the end of each day they took them away and stored them in an office maintained by the military in the Rayburn House Office Building.

"So we entered into an arrangement in which they're supposed to give us all the documents related to Benghazi," recalls the House Republican. "So they start carting these documents into a reading room. They carted in boxes and boxes and by the time [the House Select Committee on Benghazi] was created, they are carting in 25,000 pages of documents every day. The minority had their own copy. And they were stored in one of the military offices in Rayburn. The State Department guy would keep them locked up overnight."

The routine got old fast. Republicans (and Democrats, for that matter) couldn't copy the documents and couldn't use them at hearings. Chaffetz and Rep. Darrell Issa, then the chairman of the full Oversight and Government Reform Committee, became frustrated. In response to their protests, the State Department stressed that it had made all the relevant documents available, even if under restrictive conditions. State has "provided Congress with access to documents, comprising over 25,000 pages to date, including communications of senior Department officials regarding the security situation in Benghazi," State official Thomas Gibbons wrote to Issa on March 29, 2013.

That did nothing to quiet Republican unhappiness. The problem came to a head on Aug. 1, 2013, when the committee issued a subpoena to the State Department. (It was officially directed to new Secretary of State John Kerry.) The subpoena ordered Kerry to produce:

All documents that have been made available to the House Committee on Oversight and Government Reform for in camera review, including, but not limited to, the approximately 25,000 pages of documents referenced in the March 29, 2013, letter from Acting Assistant Secretary Thomas B. Gibbons to House Oversight and Government Reform Committee Chairman Darrell Issa.

To an outsider, this was the odd part: GOP committee investigators were demanding documents they were already seeing in the reading room. They weren't asking for previously-unseen materials, just for possession of what they were already allowed to see. "At the time we were fighting, the State Department had represented that they had produced everything," says the Hill Republican. "The issue we were fighting about was dominion and control of the documents. The whole purpose of the subpoena was to bring to a head the issue of possession."

Yet contrary to its claims, State had not in fact produced everything — there is now absolutely no doubt about that. "We didn't have any of Hillary's emails," the Republican says. "The State Department never made any mention of the fact that there was this [secret] email account. That fact was actively concealed from us."

Investigators were also concerned that there were few emails from key Clinton aides — Cheryl Mills, Huma Abedin, Philippe Reines, Jake Sullivan and others. "Our whistleblowers told us she had an insular world," the Republican says. "You were either part of it or you weren't." Of course, what Republicans did not know was that Secretary Clinton did her business on the secret email system, and that top aides were in on it, too.

Even though the subpoena covered what State had already produced, the old, far-reaching Chaffetz Sept. 20, 2012, letter to Clinton was still in effect, so State was still obligated to produce all the documents. Today, Republicans argue that the subpoena effectively covered not just what State had produced in the reading room, but everything that was covered by the Sept. 20, 2012, document request as well. Whatever the case, the subpoena itself seemed notably limited.

As did a second subpoena, also issued on Aug. 1, 2013. That one asked for "All documents provided by the Department of State to the Accountability Review Board convened to examine the facts and circumstances surrounding the September 11-12, 2012 attacks on U.S. facilities in Benghazi, Libya." The Accountability Review Board was the State Department's in-house investigation, and congressional investigators wanted to know what it had uncovered.

The flaw in that thinking was that, in practice, the Accountability Review Board investigation was crafted in a way to exclude examination of Clinton's actions. The investigators didn't even interview her. The subpoena for the Board's records would uncover the fact that it was wholly inadequate as an investigation, but did not discover more facts about the Benghazi episode itself.

The State Department made its last production of materials to the House Oversight Committee on April 17, 2014. In all the time from the very first document request, State had never turned over a single email to or from Clinton.

On May 8, 2014, the House Select Committee on Benghazi was created, taking over all aspects of the Benghazi investigation. Three months later, on Aug. 11, 2014, State sent a few new documents to the Benghazi committee, including a small number — less than 10 — of emails to or from Clinton. Investigators immediately noticed those emails were from an previously unknown address,

On Nov. 18, 2014, the Benghazi committee sent a document request to the State Department and to Clinton specifically demanding emails from the address. On Feb. 13, 2015, the State Department sent the Benghazi committee 850 pages of emails from two different accounts.

State said that was all the material that Clinton had given the department dealing with Benghazi. Those materials had been covered by a committee document request since Sept. 20, 2012, — nearly two and a half years earlier — and were arguably covered by the Aug. 1, 2013, subpoena. There is no doubt that Clinton withheld the 850 pages for all that time.

It was not until March 4, 2015 — a little more than three weeks ago — that the Benghazi committee issued a subpoena to Clinton for the emails. In response to the subpoena, in a letter dated Friday, March 27, Clinton's personal lawyer, the old Whitewater defender David Kendall, told Benghazi committee chairman Rep. Trey Gowdy that he, Gowdy, would have to ask the State Department for information, because State had all the relevant documents. Of course, State officials only had what Clinton had chosen to give them.

When it came to Gowdy's request that a neutral third party be allowed to inspect Clinton's email server, Kendall said its contents have been destroyed. "To avoid prolonging a discussion that would be academic, I have confirmed with the secretary's IT support that no emails from for the time period January 21, 2009 through February 1, 2013 reside on the server or on any back-up systems associated with the server," Kendall wrote. Those two dates, of course, bookend Clinton's entire term as secretary of state.

So Clinton had destroyed everything beyond the paper copies of emails she chose to turn over to State. Which raises the question: Did she destroy material under subpoena?

If Clinton destroyed the emails before January 2015, they would have been still covered by the Oversight Committee's original Sept. 20, 2012, request for documents. That request and others, as well as the Aug. 1, 2013, subpoena, were in effect through the end of 2014, but expired in January 2015 as the 113th Congress came to an end. As far as the subpoena is concerned, there is still an argument about whether it covered just the materials already available in the reading room or a broader range of material. (Whatever the case, both the request and the subpoena demanded that documents originally produced in electronic form — including emails — should be turned over to the committee in electronic form. Clinton decided on her own to print them out and destroy the data-rich electronic versions.)

Then there is the question of whether Clinton destroyed the emails after the Benghazi committee specifically asked for them on Nov. 18, 2014. That's not clear, although it seems likely she destroyed them before Gowdy formally subpoenaed them on March 4 of this year.

Whatever the case, there's no doubt Clinton destroyed evidence that was actively sought by congressional committees. And now she's telling investigators what they can do with their subpoenas.

The whole convoluted story serves to underscore the limits of congressional investigations when confronted with an executive branch determined to withhold information. Administrations have routinely ignored congressional document requests in the past, in part because when it comes to subpoenas, Congress doesn't have the power of criminal prosecutors.

"At some point with congressional oversight, we're not prosecutors," says the Hill Republican. "We're playing in a different lane than prosecutors. We can't go into the State Department and take servers and pull emails off servers. We can't conduct a raid."

"You might look at the [Aug. 1, 2013] subpoena and say there's a loophole," the Republican continued. "But the whole nature of congressional investigations is that we rely on the State Department to tell us what they are not going to give us and why."

And what if a secretary of state simply refuses to comply with a requests and subpoenas? "We can hold them in contempt or run to the U.S. attorney," notes the Republican. "But guess what? Nothing is going to happen."

The bottom line is that the system of congressional investigations has a very difficult time dealing with an official who acts in bad faith, as Clinton did in the Benghazi affair. She hid documents from investigators for more than two years, and then, when investigators wanted to see the larger group of documents from which she selected what would be released, she destroyed the whole thing.

Gowdy is determined to piece together the full story of the secretary of state's actions and communications before, during, and after the Benghazi attack. The last few weeks have shown just how tough that job will be.