"This is going to happen whether or not you want it," Nathan allegedly said to Brae as he brandished a gun in her face. "And if you're smart you'll go along with it, or you'll end up just like him."
So Brae said she did just that. When MacNeil came home July 19, 2007, from a night spent at his girlfriend's, he was attacked by the siblings, according to Brae. She said she bound her stepfather's wrists with zip ties, and then Nathan zip tied Brae's wrists. It was Nathan, Brae claimed, who shot MacNeil four times, bolted out the back door, jumped in his truck and drove back to Arizona.
But what was Nathan's side of the story? He said he wasn't even in California that day, let alone at the scene of the crime.
In a videotaped interrogation with San Diego detectives J.C. Smith and Brett Burkett, Nathan denied any involvement, and then asked to speak to an attorney.
"I need a lawyer," Nathan said. "This is too powerful ... I'm trying to tell you guys I wasn't involved."
Nathan and Brae seemed like the kids next door-- but as police delved into their backgrounds, they learned that deep beneath the surface lurked a horrible family secret.
Their mother, school teacher Doreen Hansen, had been suicidal and depressed for years. And according to many, her illness manifested itself as acute emotional, verbal and even physical abuse of Nathan and Brae.
Amid the terror of the abuse, MacNeil, who married Doreen when the kids were 4 and 6 years old, was a source of solace for the children. He was the one they felt they could trust.
In the summer of 2006, tragedy struck when Doreen MacNeil committed suicide by swallowing a bottle of pills. After Doreen's death, Nathan stayed in Arizona but Brae moved back in with MacNeil. A year later, Brae and her brother were charged with MacNeil's vicious murder -- tragically, one day after his 63rd birthday.
Two years after the crime, in March 2009, the siblings stood trial for the murder of their stepfather. Pointing fingers at each other, Brae and Nathan were set to be tried at the same time but with two different juries -- a rare legal tactic designed to expedite the trials while keeping damning evidence from one case tainting the other's jury. Brae's jury would hear her confession, but Nathan's jury would not, because it was ruled inadmissible in his case.
Before the proceedings began, the prosecution suffered an astounding blow in pre-trial hearings when a judge ruled that Nathan's confession was inadmissible because of a Miranda issue. Jurors would never hear his confession.
For the prosecution and the police, the stakes were extremely high because this wasn't the first time the case had been presented. In November 2008, Nathan went on trial for the crime by himself, but the case was declared a mistrial because of a hung jury.
In his opening statement March 23, 2009, veteran prosecutor George Bennett made sure he painted a vivid picture for the jury.
"[MacNeil] had been shot 4 times. Once in the side, once in the face, in the head with grazing wound, and then shot point blank range in the back of his head ... What the evidence shows, ladies and gentlemen, in this case, is that a conspiracy to kill Timothy MacNeil existed between Brae Hansen and her brother."
Brae's defense attorney Troy Britt told another story.