For New Jersey Gov. Chris Christie and his team of lawyers, the motives behind the Bridge-gate lane closures are somewhat baffling.

They have placed the blame of the “traffic study” scheme squarely on two people: Bridget Kelly, the governor’s former right-hand aide, and David Wildstein, the governor’s high school classmate and feared ally at the Port Authority. These two apparently acted together, keeping everyone else in the governor’s office out of the loop.

But that raises a key question: Why did they do it?

“Sometimes people do inexplicably stupid things,” Governor Christie said Thursday to Diane Sawyer, reiterating that he didn’t have anything to do with the closure of two access lanes to the George Washington Bridge, which engulfed Fort Lee in a tsunami of traffic for four days afterwards.

An internal investigation commissioned by the governor tried to explain the inexplicable, suggesting, in effect, that both Ms. Kelly and Mr. Wildstein were both a bit emotionally unstable and obsessed with a crazy idea.

But the investigation’s report – released Thursday by a team of lawyers at the Manhattan law firm Gibson Dunn, which has also been retained by the Christie administration to represent its interests in ongoing probes by the US Attorney and New Jersey state lawmakers – raises as many questions as it answers, many observers say.

The report concludes that evidence does point to the widely assumed motive of a political dirty trick against Fort Lee Mayor Mark Sokolich. The Democrat would not endorse the Republican governor, as many others had, while Christie was attempting to win reelection with a nation-impressing landslide.

But the precise reason they targeted Mayor Sokolich “is yet to be determined,” Christie’s lawyers said.

In fact, the report tries to undercut the dirty-trick theory, pointing out that Sokolich always had a “good relationship” with the Christie administration, and was even being considered for an honorary appointment. It also quoted the Fort Lee mayor saying that he found it “incomprehensible that there’s any truth whatsoever to these rumors” about a political dirty trick.

So as Christie’s lawyers purportedly scratched their heads as to why Kelly and Wildstein would have some undetermined “ulterior motive” to attack Sokolich, they suggested the two must have had some kind of personal problems that in effect left them a bit unhinged.

The report excoriates the governor’s former deputy chief-of-staff, saying “events in Kelly’s personal life may have had some bearing on her subjective motivations and state of mind.” She had to take care of a hospitalized family member during the scandal, for example.

But it also said Kelly was engaged in a romantic affair with Christie’s long-time political architect, Bill Stepien, who ran the governor’s two successful campaigns and was set to organize his expected national run for the White House. Kelly had replaced Mr. Stepien as deputy chief-of-staff for Christie – though she lacked her paramour’s experience at the post, the report said.

These two Christie aides broke up right before the “traffic study” plan, however, and the report suggests that a distraught Kelly began to plan the lane closures with Wildstein after this break-up, when she and the more-experienced Stepien no longer spoke.

“The characterization of Bridget Kelly is troublingly sexist in my estimation,” says Jeanne Zaino, professor of political campaign management at the New York University School of Continuing and Professional Studies. “In terms of the question why, the report seems to allude to the fact that Bridget Kelly was emotional, or, for some unexplained reason, decided to take out her frustration with the ending of this relationship by closing these lanes. I mean, the whole thing makes no sense.”

Wildstein, too, is described as having “crazy ideas,” and for some reason had an obsession with the Fort Lee access lanes for years, according to Christie’s lawyers. Since at least 2011, Wildstein thought it was “unfair” that Fort Lee had three access lanes to the bridge, the report said, telling officials that year that “ ‘he wasn’t crazy about the favoritism’ for certain commuters, ‘including lots of New York plates.’ ”

“Whether or not that’s the case, it certainly makes Wildstein sound crazy,” says Professor Zaino. “But it doesn’t answer the real question about the governor’s involvement in any of this.”

Indeed, the question of Kelly’s and Wildstein’s unknown motives places Christie in something of a classic Catch-22. How did these rogue aides, one part of the governor’s tight inner circle and the other appointed to a specially-created position by the governor, believe they could get away with such a public stunt, right under the governor’s nose?

“Sure, I’ve spent a lot of time in the last 11 weeks thinking about what did I do, if anything, to contribute to this,” Christie told Diane Sawyer Thursday. “And I don’t believe that I did. But I certainly was disappointed in myself that I wasn’t able to pick up these traits in these people. I’m disappointed in myself that I didn’t look closer, that I trusted too much.”

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And even as his trust was betrayed by those closest to him, the governor felt victimized by their inexplicable stupidity, he said.

“[I was] not clueless, but taken advantage of,” Christie said. “And also, more importantly, I feel like I let people down by not knowing.”