Transcript for Did Mom Conspire With Son, Brother in Murder Plot?
That's Merrill Edge and Bank of America. "20/20" continues. Once again, gio Benitez. 21-year-old Michael Bessey, another man identified as Richard Pearson. He was arrested on attempted murder and battery charges. Reporter: Even after Michael Bessey and his uncle ricc have been arrested in the attempted murder of Michael's adoptive father Robert, investigators are just scratching the surface of this case. This case kind of got out of control quickly. Reporter: That's because Robert has made a most disturbing allegation, telling police Michael has an "Unnatural" relationship with his mother, and describing a letter Michael had written to Amy with the phrase "I miss touching you." There is no question that Robert Bessey was suggesting that Amy was having an incestuous relationship with Michael. By making these allegations, he's suggesting a possible motive, that Michael, his adopted son, wants him out of the picture, so he can have his mother to himself. Robert kept insisting that Michael was getting too close to his wife, it's ludicrous. He was jealous. He was jealous. Reporter: Amy denies there was ever anything wrong about her relationship with her son. She says Robert had become delusional and unstable as Michael challenged his authority, and made it all up. Michael getting older and bigger. Robert came unraveled over the last two years. Reporter: Amy is making an alarming allegation of her own. She claims Robert wasn't just overbearing, he was physically abusive for years. It went on for a while. It went on for quite a while. Reporter: So why did you stay with him? Where was I supposed to go? What -- what was I supposed to do? Reporter: She says she'd finally had enough when Robert gave her these bruises in a big blowout six months before the shooting. He went off and it was where I was on the floor with my hands and legs in the air telling him I just want to get up. I couldn't even breathe anymore. Reporter: After that Amy got a temporary protective order, which in turn led to divorce proceedings. Given all that drama -- if Michael couldn't stand his adoptive father and wanted to protect his mom, well, who wouldn't? Hmm, god, this is hard to talk about. I hope you know that. Reporter: Amy's abuse allegations are backed up by Michael and by Amy's sisters. So what does dear-old dad say about all this? Reporter: Did you hit Amy? I'm going to take control of this situation. I won't talk about anybody in my family, and that is me taking control right now, and that is my example of controlling. Reporter: You won't say -- whether -- We're not talking about that. Reporter: Police are now exploring a new theory, that Robert's estranged wife hated him enough to have plotted his murder with Michael and uncle ricc. Were they just pawns in this game, and was Amy the queen? We suspected Amy was involved because she was the one that directly benefits from Robert's death. She's the mastermind. Reporter: But Amy told police just what she told us. Sitting here today, you can say you had absolutely nothing to do with that shooting? Positively. Absolutely. Nothing. Reporter: Her alibi? The same as Michael's, she says she was at that spaghetti dinner at her sister's house the night before, then went home and was asleep in bed when the crime occurred. Anyway, she says if she really wanted her husband dead, she could have shot him in self-defense when he got violent. For over 15 years, I slept with a shotgun at the end of my bed. I slept with my weapon next to my head. With Robert beating the crap out of me. I'm bloody. I know the laws. That would have been a righteous shoot. Reporter: A month after Michael's arrest, Amy is still in the family home with her kids, being a mom. That's when a bombshell explodes in the district attorney's office. We had a jailhouse informant send a letter actually to Sam's desk. Michael has been spilling his guts to a snitch, saying mommy had murder on her mind. As I read the letter, there were a number of details that he provided. Reporter: Among those details, that Amy had been plotting Robert's murder for months. Robert and Amy had the big blowout that spawned the whole divorce proceedings. I think that's when she started to plot his death. Reporter: But prosecutors don't think Amy's motive was her safety. Robert had already moved out of the house and was keeping his distance. No, they say, it's something much simpler, something folks in Vegas would understand -- a jackpot. She was the beneficiary of his life insurance policy. Reporter: And that life insurance policy was worth? $250,000. Reporter: And the letter also blows up Amy's alibi, and puts her near the scene of the crime. Michael has told the snitch Amy didn't stay home in bed. In fact, she drove to a diner just down the highway from the shooting, picked up Michael, and helped him get away. The noose is tightening. At that point, did you think you would be arrested? I no, I didn't have any idea about any of it. That is beyond me. That is evil. Reporter: The prosecutors aren't buying it. They charge Amy with seven different felony counts, and get ready to take her to trial.
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