Former Virginia Gov. Bob McDonnell is back on the witness stand as his public corruption trial enters its fifth week. McDonnell and his wife, Maureen, are charged with accepting more than $165,000 from former Star Scientific Inc. CEO Jonnie Williams in exchange for promoting his products.

Last week, the former governor testified about his marital problems. A key element of the defense strategy suggests that the McDonnells could not have conspired because they were barely speaking to each other. The defense also has tried to pin most of the alleged scheme on Maureen, who was not a public official.

Monday morning Bob McDonnell took the stand as William Burck, Maureen McDonnell's attorney, questioned him.  McDonnell testified Maureen eventually agreed to take medication and undergo mental health counseling amid concerns about her frequent outbursts toward him and her staff.  He acknowledged in questioning that he had dealt with outbursts from his wife for years, and that he didn't do enough to help staffers cope with her erratic behavior. He said she rejected marital counseling but did eventually agree to mental health counseling and medication.

Attorneys for Maureen McDonnell again made a motion for separate trials.  The judge denied the motion again.

Bob McDonnell testified that he had a friendship with Jonnie Williams that was independent of Maureen.  The defense referenced several texts -about Bob McDonnell calling Williams' father for his 80th birthday, a vacation to Chatham Bars Inn on Cape Cod and golfing - that were just between Bob McDonnell and Williams. 

Bob McDonnell testified that Maureen never asked him to do anything to help Williams. He also says there was never an implied understanding that he would do any favors for Williams.

Burck finished his questioning of McDonnell by asking about Maureen's reaction to being interviewed by law enforcement in February 2013. Bob McDonnell said that Maureen did not indicate that she was worried that she - or Bob - had done anything wrong. He said she was nervous after the interview and that she felt ambushed.

The prosecution's questioning of Bob McDonnell got underway shortly after Burck finished. Step-by-step the prosecution is trying to connect the dots of circumstantial evidence to show beyond a reasonable doubt that McDonnell engaged in criminal conduct.

McDonnell faced sharp questions from prosecutors about details of his personal finances.   The pointed questions prompted long pauses and lengthy explanations from McDonnell, who was admonished by the judge to just "answer the question."

McDonnell disputed U.S. Attorney Michael Dry's assertion that his joint real-estate venture with his sister was in financial trouble. Prosecutors have said McDonnell's financial desperation is what prompted him to accept money from Williams.  

McDonnell testified he knew Star Scientific CEO Jonnie Williams offered to by an inaugural gown for Maureen but he consistently said he had no idea Williams bought the designer gowns, or took her on a $20,000 shopping spree. McDonnell said he never asked whether Williams bought Maureen the many items he saw in bags from New York. Under prosecution questioning about the New York City shopping trip, Bob McDonnell testified that Maureen has a history of making inappropriate requests for money from family and friends.

McDonnell also testified that, even though he learned Williams was interested in initiating Anatabloc research at Virginia Commonwealth University and the University of Virginia from a letter written to him by Williams, he did not give back gifts his family accepted.  The gifts include a $15,000 wedding gift for his daughter, Cailin, and a $50,000 loan to Maureen. McDonnell said he was upset when he learned about the $50,000 loan to Maureen but he didn't talk to Williams about it for 30 days.  McDonnell testified that, even after the letter, he continued to accept gifts from Williams.

Dry tried to show the McDonnell's marriage wasn't broken, and that Bob and Maureen did communicate and spent time together.  Dry asked Bob McDonnell about 18 vacations with Maureen in 22 months. McDonnell admitted they took the trips, but said they were with his children and other people, not just Maureen.  Dry also displayed photos of Bob and Maureen McDonnell walking closely together into court for pre-trial hearings. In one of the pictures, the McDonnells were holding hands.

The Associated Press contributed to this article.