RICHMOND, Va. - The corruption trial for ex-Virginia Gov. Bob McDonnell and his wife plunged Tuesday into the sordid details of the couple's marriage and the former first lady's "crush" on a businessman accused of lavishing them with gifts and cash in exchange for promoting his company.

The McDonnells are charged in a 14-count indictment with accepting more than $165,000 in loans, designer clothes, vacations, and a Rolex watch from Jonnie Williams, the CEO of dietary supplements maker Star Scientific. If convicted, they could face decades in prison.

Assistant U.S. Attorney Jessica Aber said during opening statements that McDonnell and his wife betrayed the public's trust by lining their pockets with "secret gifts and cash."

McDonnell, a once-rising star in the Republican Party who left office in January, had a duty "not to sell the power and influence of his office to the highest bidder," Aber said.

"Mr. and Mrs. McDonnell knew what Mr. Williams wanted and gave it to him," she said.

Attorneys for the McDonnells told jurors the governor did what any of his predecessors would do for a Virginia-based company. They questioned Williams' character and said the couple couldn't have been scheming together because their marriage was falling apart.

Maureen McDonnell's lawyer, William A. Burck, said she was "duped" by Williams into thinking he cared for her.

Williams filled a "void" in her life, and she and her husband were pretending to be a happy couple although their marriage had "broken down" long ago, Burck said.

"They were barely on speaking terms," Burck said.

A lawyer for the former governor said Bob McDonnell will testify on his own behalf and will read an e-mail in which he begged his wife to work things out with him.

"It fell upon blind eyes and deaf ears because that evening, Maureen was distracted by other interests," defense attorney John Brownlee said.

Brownlee said the government went to great lengths looking for people to say bad things about his client, even sending investigators to interview former presidential candidate Mitt Romney and his wife, and "came up empty." McDonnell was widely mentioned as a possible Romney running mate in 2012.

Brownlee said the long hours Bob McDonnell spent at work fueled Maureen McDonnell's anger and resentment.

Burck said that Williams and Maureen McDonnell often exchanged text messages and phone calls, and that Williams often visited the executive mansion.

Burck said that the pair had a relationship that "some people would consider inappropriate" and that one potential witness may describe Williams as Maureen McDonnell's "favorite playmate." He did not indicate that their relationship was physical.