Memory is always a liar, former senator Bob Kerrey once told Greg Vistica, in one of the most shocking investigative stories I’ve ever read about an American politician.

Former Nebraska senator Bob Kerrey (D) is planning to run for Nebraska's open U.S. Senate seat this year. (Mark Lennihan/AP)

Which would explain, I suppose, why, since Kerrey’s signalled he’s back in the business and mulling a run for his old Senate seat in Nebraska, there’s been more happy talk about how the well-liked Kerrey (D) once bravely refused partisan orders to trash the GOP’s Bob Dole, “his fellow war hero,’’ as MSNBC’s Lawrence O’Donnell put it, than there has been focus on the by-any-measure troubling accounts of Kerrey’s actions as a 25-year-old lieutenant in the Vietnamese hamlet of Thanh Phong.

In the telling of former Navy SEALs, unarmed civilians — women, children, even a baby — were killed on Kerrey’s order that night, during a mission gone terribly wrong. Kerrey’s own retelling is more complicated, but hardly problem-free.

“While witnesses and official records give varying accounts of exactly what happened,’’ the story in the New York Times Magazine said, “one thing is certain: around midnight on Feb. 25, 1969, Kerrey and his men killed at least 13 unarmed women and children. The operation was brutal; for months afterward, Kerrey says, he feared going to sleep because of the terrible nightmares that haunted him.”

In the article, Vistica writes, “Did Kerrey and his men commit crimes of war, or were they just applying the basic rules of a dirty war as best they understood them?”

Kerrey responds: “Let the other people judge whether or not what I did was militarily allowable or morally ethical or inside the rules of war. Let them figure that out. I mean, I can make a case that it was.”

Among the many questions the story raises for me is this one: Are there acts so repulsive that they disqualify one outright for public service?

That’s for voters to say, of course, though if potential war crimes don’t fall into that category, it’s hard to imagine what those “practitioners of the dark political arts” I wrote about today could possibly dig up that would.

This question is of particular concern to me because I don’t know the answer. And because, as the conservative site NewsBusters never wearies of pointing out, one of the politicians I’ve admired most was Ted Kennedy, who in my view was indeed culpable in a young woman’s death, and spent the rest of his life trying to atone for it.

(What NewsBusters doesn’t note is that “Hardball” clip of me eulogizing Kennedy was taped ... right after he died. I also have what some might consider puzzling soft spots for Rick Santorum and Nancy Pelosi, Michele Bachmann and our current president, all for different reasons, though those of us who won’t stay put in our pigeonholes are vexing to ideologues, I realize.)

Another question the early coverage of Kerrey’s reemergence on the political stage raises is this: Do we in the media ever tire of giving the grown-up equivalent of the popular kid in class a pass?

Okay, that one wasn’t serious; in my view, no.

Melinda Henneberger is a Post political writer and anchors the paper’s “She the People” blog. Follow her on Twitter at @MelindaDC.