Former Virginia governor Robert F. McDonnell had just explained, with a heart-breaking letter and a sotto voce delivery, that his marriage was in shambles. He went on from there to describe how those personal woes sucked him into a public corruption case.

He testified that first lady Maureen McDonnell was seeking money, attention and maybe even affection from a charming, free-spending businessman. McDonnell told the jury he was in the dark about his wife’s affairs, both financial and (non-physically) romantic.

And so the first criminal case in history against a Virginia governor could come down to this: Does McDonnell, self-professed micromanager and 2012 vice presidential prospect, make a convincing chump?

“Maureen, I manage the finances,” McDonnell said he told his wife upon learning (belatedly, he claimed) that she had borrowed $50,000 from then-Star Scientific executive Jonnie R. Williams Sr.

Did he manage them or not?

List of gifts given to the McDonnell family from Jonnie Williams.

That will be one key question for jurors when they weigh whether the first couple corruptly lent Williams the prestige of the governor’s office in exchange for $177,000 in luxury gifts, vacations and loans. The spectacle of Bob McDonnell’s testimony — by turns skittish, coolly confident, emotional, fuzzy and contrite — could largely determine their answer.

The former Republican governor has so far testified for more than 12 hours over three days. Under the gentle questioning of his defense attorney, he has portrayed himself as humble, devoted to the commonwealth — and utterly blindsided by the depth of his wife’s entanglements with Williams. He’ll continue this week, when prosecutors get their chance to challenge his account in cross-examination.

“He’s created an alternate narrative to what happened,” said Kelly Kramer, a white collar criminal defense lawyer at the Mayer Brown firm. “He’s not negating the government’s case in its entirety, but he’s providing a different spin on things.”

McDonnell told jurors he didn’t know his wife was decked out in designer fashions; he wears off-the-rack Jos. A. Bank. He never dreamed how pricey tee times could be at Williams’s private country club, where the governor and his sons golfed several times. Even the pro shop purchases that pumped their tab for one golf outing above $1,000 seemed to come as a surprise.

“Somehow we did end up with some shirts,” he said.

But McDonnell did not plead ignorance on everything. He can’t: Texts, e-mails, phone records and other documents prove his knowledge of at least some of Williams’s gifts and loans.

McDonnell acknowledged that he knew that Williams gave the first lady $15,000 to cover the catering tab at his daughter Cailin’s wedding. He said he was “astounded” to learn Williams dropped off a second check — for the $50,000 loan — the same day, but told jurors he found out soon after and did not return the money.

‘Innocent explanations’

While the defense has contended that the couple’s marriage was so broken they could not possibly have engaged in conspiracy, McDonnell told jurors that his wife initially talked to Williams about a separate loan for his real estate company, but the governor later hashed out the terms with the Star chief. By the governor’s own account, when it came time for the men to work out the nuts and bolts of what became a low-interest, $50,000 loan, Maureen McDonnell might have been talking with Williams first and then handed the phone to the governor.

And no matter what gifts he or his family accepted, McDonnell told jurors he never made any agreements to help Williams or Star. There was no bribe, he testified, no corrupt deal. He said anything he did for the executive was in line with ordinary political courtesies and unconnected to the executive’s largesse.

“If the jurors credit his testimony, I think he’s established reasonable doubt,” said Edward T. Kang, a former federal prosecutor who now does white collar work at the Alston & Bird firm. “He’s presented innocent explanations for most, if not all, of the most damaging evidence that the prosecution has laid out.”

Many of those explanations revolve around a personal soap opera.

In Bob McDonnell’s telling, it stars an insecure, possibly mentally ill first lady. And an earnest but overextended public servant who has ascended so high that he can no longer manage, much less micromanage, his swelling responsibilities. He is forced to delegate, allowing a suave and ultimately untrustworthy salesman to play a greater role in his wife’s life.

The climax, at least last week, came when the jury was shown a letter that McDonnell had written to his wife in September 2011, begging her to work with him to save their marriage. Judge James R. Spencer stopped McDonnell from reading the missive aloud. But jurors could read it.

“I am completely at a loss as to how to handle the fiery anger and hate from you that has become more and more frequent,” McDonnell wrote. “You told me again yesterday that you would wreck my things and how bad I am. It hurt me to my core.”

While that defense is highly unflattering to Maureen McDonnell, it is a story line that her own legal team has pushed as vigorously as her husband’s. Because the first lady’s position is a ceremonial one with no official powers, she cannot be accused of trading any official acts in her own right. Prosecutors are trying to prove that she engaged in a conspiracy with her husband. The McDonnells claim they were too estranged to work together on anything.

Marriage in the spotlight

The defense’s strategy means pulling back the curtain on a marriage that in public once appeared full of love and romance: Bob McDonnell carried his wife over the Executive Mansion threshold the day he took office in January 2010.

Even if jurors are convinced that the marriage was deeply troubled, the strategy of showcasing dirty family laundry carries significant risk, Kramer said.

On one hand, it posits a compelling alternative to prosecutors’ theory of the case, suggesting that the McDonnells were not a greedy, scheming duo hungry for Williams’s money, but rather, a struggling, sympathetic couple too mired in their own problems to fully consider what was happening.

On the other hand, the tactic might come across as the governor unfairly blaming his wife in a desperate attempt to save himself.

“Some of the things that the jurors are going to think about is whether or not McDonnell’s story is contrived, whether or not this is just a convenient excuse,” Kramer said. “And I’m sure the prosecutors will suggest that.”

Taking the stand is a risky move, even for a practiced communicator who in his heyday popped up regularly on “Meet the Press.” It is one that Maureen McDonnell is not expected to take.

If nothing else, the trial has provided dramatic proof of just how little the public knew about what was really going on with its state’s chief executive during his time in office, despite the intense spotlight in which he operated.

By day, McDonnell kept an almost frenetic pace of state and political business, giving off the air that he was always prepared and engaged in his work, never a hair out of place. By night, he was navigating his intensely complicated personal finances as he worked to pay down vast debt spread across multiple credit cards and refinance several expensive properties.

By his account from the witness stand, his wife’s issues were a constant struggle. The staff at the mansion was in revolt. He served as adviser to his sister, whose own marriage was falling apart. Even as he steered a state that’s home to more than 8 million, Bob McDonnell also found himself saddled, as one e-mail showed, with lining up carpet cleaning for the family’s Virginia Beach rental homes.

Jurors might be convinced that the crush of McDonnell’s responsibilities kept him from fully grasping what was going on between Williams and his wife. But they might also find it hard to trust a man who so effectively hid his personal turmoil for so long.