Greensboro, North Carolina (CNN) -- The wife of a former top aide to former presidential candidate John Edwards defended in testimony Tuesday having shot video in September 2008 of the house and possessions of Edwards' pregnant mistress.
"I wanted proof that I really was taking care of Rielle Hunter," said Cheri Young, whose husband, Andrew, was a top aide to the then-candidate for the Democratic presidential nomination, who is now facing federal corruption charges.
Defense attorney Alan Duncan showed the jury the videotape of the North Carolina house leased by Hunter, who was in California and had not given her consent to the taping. A number of personal pictures, Hunter's California driver's license and a tentative list of baby names were shown to the camera.
Young said she had not asked Hunter for permission because she assumed Hunter was out of the country on a trip planned by Edwards' benefactor Fred Baron. "I wasn't looking through Ms. Hunter's private things," Young said.
Asked why she was videotaping Hunter's private items, Young responded, "Things had gone sour" between the Youngs and Edwards, and Young wanted to be able to show that the money given to herself and her husband had, in fact, been spent on Hunter for such items as a lease on a house and furniture.
Earlier in the day, Young had defended her husband's motivations for writing a tell-all book about him.
"The only reason for my husband to write a book is because Mr. Edwards did not come forward and tell the truth," she testified.
She was responding to questions from Duncan about profits from the book.
Young pointed to an interview with ABC News in August 2008 during which Edwards did not acknowledge having fathered a child by Hunter as a critical moment in the decision to write "The Politician: An Insider's Account of John Edwards's Pursuit of the Presidency and the Scandal That Brought Him Down."
"It was discussed as a way to completely tell the truth in 2008," she said. "I wanted the truth to come out."
The defense pointed out that Cheri and Andrew Young stand to make more money if the book is used as the basis for a movie about the disgraced politician. "Would you like to get additional income from the movie being made?" the defense lawyer asked.
To that, Cheri Young offered no apologies. "Yeah, I'll take income," she said.
But she maintained that the only reason she was still involved in the story was because of the court case. "I came here because I had to come here," she said.
The defense also said Young has little first-hand knowledge of the events, i.e., that most of what she knew she learned second-hand from her husband, not from primary sources. Young testified that she had not been in the same room with her husband when he made many of the calls that have been cited in the case.
The defense also tried to assert that Andrew Young was drinking heavily in 2006 and 2007, that it affected his memory and that he was mixing alcohol and Ambien.
The prescription medication is used in the treatment of insomnia. Its combination with alcohol can increase the chance that a person taking the medication will experience side effects, according to the package insert.
The defense added that Andrew Young's work for Edwards was a source of tension in their marriage, which caused Cheri Young to resent her husband. She denied the claim.
Cheri Young had testified Monday that Edwards told her that using money from one of his benefactors to pay his mistress's expenses was legal.
"Get the money in," said Edwards, who was then running for president, Cheri Young recalled Monday.
Prosecutors say those donations, which weren't reported to federal authorities, were illegal and represent a chief reason Edwards is being tried on six felony counts. Also charged with conspiracy and making false statements, he could face up to 30 years in prison if convicted on all counts.
Young testified Monday that she felt "disgusted" after being asked to endorse and deposit checks from 101-year-old heiress Rachel "Bunny" Mellon intended to pay Hunter's expenses.
Edwards, who was then married, eventually admitted having carried on an affair with Hunter, whom his campaign had hired as a videographer, and fathering her child.
Cheri Young sobbed on the stand Monday after explaining her reaction to being told that Edwards wanted her husband to claim that he was the father of Hunter's child.
"The first thing in my mind was how in the world Mr. Edwards could ask one more thing of us," Young said of her thoughts at the time.
Despite her reservations, Young said she participated in a December 2007 conference call with her husband, Edwards and the then-pregnant Hunter.
"Mr. Edwards was trying to get everyone on board," Young testified. "(He talked) over and over about the campaign."
She said Edwards also said that he didn't want his wife, Elizabeth, who had been diagnosed with cancer, to find out about the affair and child. Elizabeth Edwards died of breast cancer in December 2010.
Andrew Young did once claim to be the father of Hunter's child, though Edwards -- after losing his bid for the Democratic nomination -- acknowledged that the child was, in fact, his.
He is accused of concealing $725,000 in contributions from Mellon and more than $200,000 from Texas lawyer Baron, who has since died, from the public and from the Federal Election Commission by filing false and misleading campaign disclosure reports.
Edwards' attorneys have argued that Andrew Young was involved in a ruse to extract hundreds of thousands of dollars from donors for his personal use.
The former aide admitted during questioning by Edwards' attorney that he used campaign donations for his own benefit, including to fund construction of a home that included a pool and a theater.
CNN's Ted Metzger, Eric Fiegel, Oliver Janney and Scott Garber contributed to this report.