Tylar Witt still brags about her mom.
Joanne Witt's master's degree in mechanical engineering, her skill in the kitchen and her tomboy traits are all sources of pride for her teenage daughter.
"She was a lot like a dad," Tylar said. "What other mom catches snakes and lizards and puts them in aquariums?"
But the affection Tylar shows today was critically absent on June 12, 2009 -- the day, prosecutors say, Tylar helped her boyfriend kill her mother.
"I don't think I ever appreciated what my mom did for me," she told "20/20." "When you are a kid, the only thing that you see are [parents] doing stuff for you and then them punishing you."
Joanne Witt was a single mother raising her only daughter in a wealthy gated community in El Dorado Hills, Calif. She stopped seeing Tylar's father while she was still pregnant and was determined to raise Tylar on her own. An accomplished engineer, Joanne Witt provided her daughter with everything from acting courses and riding lessons to adventurous site-seeing trips. They also spent quiet evenings at home, cooking together and watching movies.
But moments of mother-daughter bonding were belied by a long-standing friction.
When Tylar was in pre-school and a teacher noticed suspicious bruises on her face and body.
Tylar's aunt, Mary Witt, said that Joanne Witt once flew into a rage while driving Tylar, who was then a pre-schooler. She pulled the girl out of the car, hit her with a belt and slapped her.
"She was just bruised all over," Mary Witt said.
Tylar's pre-school teacher noticed the bruises and informed authorities. Tylar was taken away from her mother for several months and Joanne Witt was ordered to take anger management classes. The mother vowed never to let something like that happen again.
Tylar said there were no more beatings, but there were loud arguments, often fueled by what Tylar says was her mother's secret drinking problem. Another source of tension was Tylar's questions about her biological father -- questions Joanne Witt didn't want to answer.
Joanne Witt "didn't want him in her life," Mary Witt said.
But the biggest battle would come when Tylar turned 14. She met an older boy, 19-year-old Steven Colver, at a shopping center. Nicknamed Boston, Colver dressed in black, Goth clothing but had a job, attended community college and, according to Tylar, was a great listener.
"I had a really, really bad day," Tylar remembered. "I called him up and said 'I just need someone to talk to.' He would come by my house and we would just talk."
Tylar started calling him her "big brother" and they told Joanne Witt they were just friends, as close as a brother and sister. Tylar even told Joanne that he was gay, according to Mary Witt.
Joanne Witt was so comfortable with Tylar and Colver's friendship that when Colver needed a place to live, she invited him to live in a spare room in the house for $500 a month.
"He was going to be part of the family," Mary Witt said.
But soon there would come clues that Tylar and Colver were more than just friends. Mary Witt said Joanne noticed the two were "a little more chummy" than she had anticipated.
A surprise visit to Colver's room soon confirmed her suspicions: She found both of them there and Tylar was naked, hiding in the closet.
"She found out that they were having sex there and she just couldn't believe it. She just started screaming, you get out of here," Mary Witt said.
Tylar Witt and Steven Colver: Pulled Into a 'Dark Orbit'
Colver moved out. Joanne Witt, meanwhile, called the police and accused Colver of statutory rape. (Listen to a police deputy's follow-up phone call to Colver here.) She handed them Tylar's personal diary, which included pages filled with graphic descriptions of the illegal sex between the 14-year-old and the 19-year-old.
Fearing they'd have little time before Colver was carted off to jail, the two lovers made a pact. They would become an actual Romeo and Juliet -- killing themselves on a special date, at a special place: In San Francisco on their three-months and three-weeks anniversary.
But they planned to kill someone else first: Tylar's mother.
Looking back, Tylar said it doesn't make any sense now, but somehow, back then, it did. The teens believed that if they didn't kill Joanne Witt, she would get in the way of their suicide plans.
The couple had "created this alternative reality where their entire existence is in peril," said Peter Hecht, the Sacramento Bee reporter who followed the case. "The kids went into their own dark orbit. And nobody could pull them out of it."
The police found Joanne Witt dead in her bed, the victim of 20 stab wounds. When they determined Tylar and Colver were missing, a manhunt began.
But the star-crossed lovers had planned to be dead before police could find them. After burning their clothes and dying their hair, they set off for San Francisco. There, Tylar said the couple tried -- and failed -- to carry out their suicide plans, spiking their food with rat poison.
"We ingested a good amount of rat poison," she said. But the poison produced little more than a stomach ache for Tylar.
Spooked by TV news reports about the manhunt, Tylar and Colver abandoned their car and their San Francisco hotel room. They were right to be worried -- police were hot on their trail. After spending a night in a cemetery in a San Francisco suburb, the couple was spotted outside a shopping mall by an off-duty police officer.
After their arrest, Colver pledged his love to Tylar, asking his attorney to relay to Tylar a message that "nothing has changed."
Colver's mother and his defense attorney believe that the message was code for sticking to a plan for Colver to take the blame for Joanne Witt's murder.
But after the two lovers sat in jail for a while, stories began to change. Colver, who had at one point described to friends how he'd stabbed Joanne Witt with a butcher knife, began to claim that it was Tylar who did the stabbing. He said he only arrived at the Witt home after Tylar had already killed her mother.
"I think realizing the gravity of the situation after being in jail for a while, it took a while before he was willing to confirm, yeah, that she had done it and how she had done it," said Colver's defense lawyer, Dain Weiner.
Tylar said she'd been betrayed and it hurt.
"It's like somebody telling you that they are gonna love you no matter what, and you have depended on them, and then they take it away."
Tylar told prosecutors that after Joanne "passed out," she called Colver, who came over. When the pair neared Joanne's bedroom, prosecutor Lisette Suder said, Tylar "freaked out," and dropped to the ground in the fetal position.
"She is right there outside the door, so she hears rustling and realizing at that point that he is, then, stabbing her mother," Suder said.
But the "freak out" moment, Tylar told prosecutors, didn't last long. She quickly recovered and began directing the cover up, pulling the drapes closed and turning up the air conditioner.
"She didn't want Steven to be touching anything because he had blood," Suder said.
Colver told a different story: He said he arrived at the Witt home only after Tylar had already stabbed her mother. He said he agreed to run away and commit suicide with his girlfriend -- but the murder was a total surprise.
Jurors didn't buy Colver's account. On August 12, 2011 the jury in the case found him guilty of first-degree murder and sentenced him to life without parole. Tylar was convicted of second-degree murder and received a reduced sentence -- 15 years to life -- in exchange for testifying against Colver.
Tylar says she has apologized to her mother and admitted her guilt in setting Joanne Witt up for murder at the hands of Colver. But Tylar still finds room in her heart for her Romeo.
"I can't be angry at him -- I was part of it," she said. "How can you be angry with somebody when they did exactly what you were doing? That's being a complete hypocrite. You love somebody no matter what."
Still, she said she agreed with Colver's life sentence. She felt hers, however, was too final for a girl who is only 16.
"My mom was not a vicious person and she didn't hold grudges. And even if something horrible like this would have happened, she would have asked for a just punishment. She wouldn't want to see someone suffer for the rest of their lives for a mistake they made when they were being ignorant and stupid."