Martin MacNeill's mistress Gypsy Willis took the stand Tuesday to testify in his murder trial regarding the mysterious death of his wife Michelle in April 2007. Michelle died following a facelift operation.

Willis, 37, told the court that her affair with Martin, 57, began in November 2005 after the two met online. She said that they would meet up twice a month and that their relationship was sexual beginning in January 2006. She admitted that she also sent him suggestive photos the day after his wife's funeral and participated in a staged public meeting after a year and a half of dating, soon after the funeral.

Martin and Michelle's daughter Rachel told the court Thursday that Willis was introduced under the premise of being a new nanny for her younger siblings after Michelle's death, but it was soon clear that Willis and her father were engaged in a romantic relationship when she didn't seem to do any work around the house.

Willis testified that Martin proposed to her with a 4.5-carat engagement ring in July 2007, three months after his wife's death, and told the prosecuter that she believes he was serious about them getting married. Prosecuters believe that Martin committed the alleged murder in order to be with Willis. MacNeill had a fictitious wedding date of April 14, 2007 listed – the day of Michelle's funeral – but Willis testified that they had never gotten married.

Rachel testified that her father insisted on having an autopsy done after her mother's death so that he wasn't suspected of murder, which she found suspicious. Rachel said that the day her mother died, she found her wet, blood-stained running clothes piled in the garage. When she showed them to her father, who is accused of drowning his wife in the bathtub after overmedicating her post-surgery, he reacted defensively. Willis admitted to knowing about Michelle's plan to undergo facelift surgery, but has not admitted to knowing anything about a murder plot.

Rachel, her sister Alexis, and her Aunt Linda Cluff campaigned for five years before MacNeill was charged with murder.

Though Willis' defense lawyer Susanne Gustin said that Willis has promised to tell the truth about what she knows, both prosecuting lawyer Sam Pead and Judge Derek Pullan agreed that her testimony was aligned with the goal of protecting Martin.

Martin was a well-respected doctor and lawyer preceding the trial. He pleaded not guilty to first degree murder, saying that his wife died from natural causes due to heart disease. If found guilty, he could face life in prison.

Martin and Willis have a past in regard to trouble with the law. The two were convicted of identity theft in 2009 when he left his adopted daughter in her native Ukraine so that Willis could assume her identity. Willis served a 21-month sentence and agreed to testify in order to reduce further time in prison.

A second mistress, Anna Osbourne, is expected to testify soon regarding MacNeill's alleged confessions to murdering other people.

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