Marissa DeVault's secret lover took the stand in her murder case, testifying that she told him that she wanted to kill her husband before she actually committed the crime.

DeVault is on trial at Arizona's Maricopa County Superior Court for the first-degree murder of her husband, Dale Harrell, 34. The 36-year-old mother of three used a claw hammer to bash Harrell's head while he was sleeping on Jan. 14, 2009. He suffered from multiple skull fractures and died almost a month later in a hospice.

DeVault argues that he abused her in the past and says she killed him in self-defense, however, prosecutors contend that she murdered him in order to collect his almost $300,000 life insurance policy and pay off a $360,000 loan to her secret boyfriend.

According to AZcentral, DeVault and her lover, Allen Flores, 56, met two years before she killed her husband through a website that arranges relationships between "sugar daddies" and women in financial need.

Flores, who has been granted immunity from prosecution for possession of child pornography in exchange for his testimony, took the witness stand on Monday. He revealed that he lent DeVault $362,000 over two years of their relationship and that he kept detailed accounts of each transaction.

"I loved her, she was in trouble, I was trying to help," Flores said on the stand.

In addition, Flores, who has an MBA from Yale University and a Ph.D from a university in England, testified that DeVault told him she was considering killing her husband.

Originally, she told police that Harrell had choked and raped her. Flores bailed her out of jail and hired a lawyer on her behalf. However, DeVault then changed her story, claiming that her housemate, Stanley Cook, had attacked Harrell while protecting her.

Flores went on to say that DeVault and Cook approached him with a false confession in which he took the blame for the attack.

On Tuesday, Cook took the stand, professing that he does not remember what happened on the night that Harrell was murdered. Although Cook lived with the couple and apparently witnessed the attack, he says a brain defect has impaired his memory.

"I don't remember that night," he told prosecutors, according to AZcentral. "It was five years ago. I have trouble remembering last week."

He also added that he didn't think Harrell was abusive to DeVault. When Cook was asked if he ever saw Harrell abuse DeVault's and Harrell's three children, he answered, "Probably not; if I had seen it, I would have stopped it."