August in Washington can be the political equivalent of an elephant graveyard: One good rain can wash away the dirt and expose the bones of scandals past.

And this August did not disappoint. Thanks to the relentless investigative work of Senate Finance Committee Chairman Chuck Grassley (R-Iowa) and Senate Homeland Security and Governmental Affairs Committee Chairman Ron Johnson (R-Wis.), we are learning that the Hillary Clinton email case may not really be settled.

A staff memo updating the two senators' long-running probe discloses that the FBI - the version run in 2016 by the now-disgraced and fired James Comey, Andrew McCabe and Peter Strzok - failed to pursue access to "highly classified" evidence that could have resolved important questions.

The failure to look at the evidence back in 2016 occurred even though the agents believed access to the sensitive evidence was "necessary" to complete the investigation into Clinton's improper transmission of classified emails - some top-secret - on her unsecure private email server, the memos show.

To make matters worse, the Trump Department of Justice (DOJ) has known about that decision since at least 2018, thanks to the work of the DOJ's internal watchdog, Inspector General (IG) Michael Horowitz, who provided DOJ leaders and Congress with a classified appendix explaining what happened.

But Johnson and Grassley have been unable to get answers for a year, even from Attorney General William Barr, about whether the FBI intends to look at the critical evidence it skipped back in 2016.

The Senate staff memo succinctly lays out just how egregious the FBI's decision was in 2016.

The inspector general's "appendix raised a number of serious questions because, as explained on page 154 of the unclassified DOJ IG report, the FBI decided not to seek access to certain highly classified information potentially relevant to the investigation despite members of the FBI case team referring to the review as a 'necessary' part of the investigation," the Senate staff wrote.

"As a result of the findings in that appendix, Senator Grassley wrote a classified letter to DOJ on October 17, 2018, which remains unanswered. On January 15, 2019, at Mr. Barr's nomination hearing, Senator Grassley asked Mr. Barr if he would answer the letter, if confirmed, to which he attested, 'Yes, Senator.' On April 16, 2019, Senators Grassley, Johnson, and Graham sent a letter to Attorney General Barr reiterating the need for a written response to that letter."

The DOJ's silence on the road that the FBI willfully chose not to take is all the more deafening given what we already know about the Clinton email case.

As I previously wrote, then-FBI Director Comey's original draft findings in the Clinton case concluded her transmission of classified emails through an unsecure server was "grossly negligent," the legal standard supporting a felony charge under the Espionage Act.

But the findings were edited and the term changed to "extremely careless," and Comey chose on his own to announce on July 5, 2016, that he would not seek criminal charges, a decision that the DOJ's IG concluded had wrongly usurped prosecutors' authority to make charging decisions.

In addition, as I have written, FBI general counsel James Baker believed - almost until the last minute before Comey's announcement - that Clinton should, in fact, face criminal prosecution, but he was talked out of it.

And in a passage that often gets overlooked by reporters and pundits alike, IG Horowitz concluded in his final report about the Clinton email caper that the anti-Trump biases that FBI agent Strzok and bureau lawyer Lisa Page expressed in text messages may have affected their decisionmaking to focus more urgently on the now disproven Trump-Russia collusion allegations rather than to finish work on the former secretary of State's email problems, an investigation code-named Midyear.

"In assessing the decision to prioritize the Russia investigation over following up on the Midyear-related investigative lead ... we were particularly concerned about text messages sent by Strzok and Page that potentially indicated or created the appearance that investigative decisions they made were impacted by bias or improper considerations," the Justice Department's watchdog wrote.

So the FBI's chief lawyer originally thought Clinton should be indicted, and the bureau wrote a draft supporting the felony standard, but then walked back its decision. And agents focused more on unsubstantiated Trump collusion than Clinton emails in what the IG feared might be a sign of bias.

And now we learn the FBI willfully chose to ignore highly classified evidence in the Clinton email case and has stonewalled Congress for a year on whether it intends to reexamine that evidence.

It's exactly that sort of behavior that leaves many Americans wondering whether there are two systems of justice inside the FBI - one for the Clintons, and one for the rest of the country.