Updated: A former top aide to the Senate Armed Services Committee now says the committee was never made aware of the incidents in Shanahan’s past when it took up his nomination to be deputy defense secretary in 2017. The aide has called for accountability. This post has been updated with his comment.

Patrick Shanahan’s bid to become defense secretary has been withdrawn, and The Washington Post’s Aaron C. Davis and Shawn Boburg have the big story about why. Reports about two incidents of domestic violence — one in which Shanahan’s then-wife was charged with assaulting him and another in which his then-teenage son hit her with a baseball bat in the head — have led President Trump to announce Shanahan’s withdrawal.

The first, inescapable emotion one has to have while reading the story is sadness. It’s an extremely messy family situation that sounds awful and painful.

But the other thing I felt is curiosity: How is it possible Shanahan thought he could become secretary of defense without this being publicized and litigated? And beyond that, how was he picked for the job in the first place, and how was he previously confirmed as deputy secretary of defense?

There are certainly many questions here — regarding Shanahan, the White House that picked him, the FBI that conducts background checks and the Senate, which confirmed him in the deputy position.

From Shanahan’s perspective, it’s important to emphasize that he was never charged with becoming violent himself, though his wife did accuse him of that. But in interviews with The Post, he admitted fault for having suggested his son’s assault of his mother was justified as an act of self-defense. He had initially suggested she had drawn the attack by harassing the teenager over a period of hours. “I was wrong to write those three sentences,” he said of a memo in which he made that case.

Shanahan would surely have been forced to account for that situation and others. Now, he has pulled out before he could even really attempt to.

But why was he in contention in the first place? In the vetting process, the first things to check are divorce records, police records and court records. The Post’s reporting relied upon all three. The White House has never been big on actually vetting its nominees — even for top Cabinet posts — but is it really possible it didn’t check these very basic boxes? And it would seem very likely that an FBI background check was conducted that would provide such information to the White House counsel. Was that done? Either someone was negligent, or someone turned a blind eye.

And even setting that aside, did the GOP-controlled Senate dig into these things when it was confirming Shanahan as deputy defense secretary in July 2017? Shanahan was confirmed 92 to 7, despite some concerns about installing a former Boeing executive as a top Pentagon official. As Davis and Boburg noted, all three of his children sat behind him at the hearing; domestic violence didn’t come up once.

Update: Chris Brose, the former staff director for the Senate Armed Services Committee’s (SASC) Republican majority, says the committee was never made aware of the incidents in Shanahan’s past.

“The first I learned about this was in the media today," Brose tweeted Tuesday night. "SASC deserves to know why.”

At least one Democratic senator, Richard Blumenthal of Connecticut, is already raising the prospect that Shanahan might have withheld this information on his disclosure forms.

“I feel there was a deliberate concealment here,” Blumenthal, a member of the Senate Armed Service Committee, told reporter Matt Laslo. “This is potentially a violation of criminal law.”

This is merely the latest vetting failure from the White House. It previously employed Rob Porter as staff secretary despite two ex-wives having accused him of physical abuse. It nominated and then withdrew Ronny L. Jackson for Veterans Affairs secretary despite some very serious accusations that quickly came to light. Trump’s first labor secretary nominee, Andy Puzder, quickly succumbed to accusations of domestic violence and employing an undocumented worker. And you could even throw now-Supreme Court Justice Brett M. Kavanaugh in there; even though he wound up winning confirmation, it was made much more difficult by sexual assault allegations against him.

In some of these instances, it’s perhaps somewhat understandable how these things could have slipped through the cracks; Kavanaugh had never been accused publicly, for example, and Jackson’s reputation was solid from when he served in the Obama White House. In the case of Shanahan, these are public records. The Post has been asking Shanahan about these incidents since January, when he became acting secretary, and when Trump announced he intended to nominate Shanahan for the permanent job last month.

It’s a remarkably sad story — and one that many people involved probably should have prevented from ever needing to be told in the context of a Cabinet nomination.