After spending nearly three years and countless millions of taxpayer dollars, the federal investigations into the September 2012 attacks on the U.S. compound in Benghazi, Libya, which killed an American ambassador and three other U.S. citizens, have thus far yielded no proof that the Obama administration orchestrated a cover-up to conceal either a failure to prevent the attacks, or a bungled response in the aftermath.

The House Select Committee on Benghazi was supposed to change that. Created to deliver the final word on the long-running saga, the committee headed by Rep. Trey Gowdy (R-S.C.), a former prosecutor, has the funding, the jurisdiction, and the subpoena power that lawmakers said would be necessary to bring an end to the debate over what happened in Libya in 2012.

However, in an interview with his hometown Greenville News, Gowdy over the weekend set out to lower expectations. Turns out that millions of dollars and thousands of person-hours of work don't necessarily buy you a whole lot of certainty.

"If you do a good enough job laying out the facts, the conclusions will either speak for themselves or you'll have competing factual narratives and you can draw your own conclusions," Gowdy told the paper.

"It's not my job to tell people what to conclude," he said. "If you have two witnesses, [and] one says the light was red and one green, I don't view myself as being the arbiter of who is more credible."

In the end, he said, "People are going to draw different conclusions. That's fine."

In a way, Gowdy was making a somewhat pedantic point about the nature of any investigation. It will always, of course, be possible for people to challenge, or even deny, facts that don't fit their preferred version of events.

But when the combined cost of the multiple investigations into the Benghazi attacks gets calculated — and it will — plenty of people, chief among them congressional Democrats, aren't going to be pleased with an "one the one hand, one the other hand" conclusions. They long ago concluded that the Benghazi investigations are chiefly political in nature, meant to raise doubts about Democratic presidential frontrunner Hillary Clinton, who was secretary of state at the time of the attacks.

Earlier this month, for example, Gowdy released a one-year progress report on the investigation. Among other things, he announced that the committee will not call Clinton to testify until it is satisfied that it has received all of the necessary information from the State Department. Gowdy also hinted that the investigation would likely not be concluded until 2016 — the year of the next presidential election.

"At every turn, the Select Committee comes up with a new excuse to further delay its work and then blames its glacial pace on someone else," said Rep. Elijah Cummings (D-Md.), the committee's top Democrat. "Republicans are desperately trying to validate the $3 million in taxpayer funds they have spent over the past year, but they have nothing to show for it other than a partisan attack against Secretary Clinton and her campaign for president."

Adam Smith (D-Wash.), the top Democrat on the Senate Armed Services Committee, said: "The Republican Progress update and admission that the final report won't be made public until 2016 begs the question: What have we spent $3 million dollars on? Their lack of any real progress makes clear that this Committee's goal isn't a legitimate investigation — it's a $3 million dollar publicly financed political attack committee."

The $3 million price tag on the Select Committee's investigation is, of course, only the beginning.

The Federal Bureau of Investigation has been investigating the attack from the start, and its work is ongoing.

Other congressional investigations have been undertaken by the Senate Select Committee on Intelligence, the Senate Committee on Homeland Security and Government Reform and no fewer than five separate House committees (Armed Services, Foreign Affairs, Judiciary, Intelligence, and Oversight and Government Reform.)

There is currently no good data on the total amount spent investigating Benghazi. But at its current rate, the House Select Committee will likely spend some $6 million by next year, and the multiple other congressional investigations likely spent similar sums. That doesn't take into account the costs incurred by other government agencies in connection with the investigations. Last year, for example, the Pentagon reported that it had spent millions of dollars on complying with repetitive requests for information from the multiple investigating committees.

When Gowdy wraps things up in 2016, he may think it's "fine" to deliver a finding that doesn't claim to finally put the questions about Benghazi to rest. But it's not clear taxpayers will agree.