06/15/2011 at 06:10 PM EDT
It took a Northern California jury only a few hours Wednesday to convict Steven "Boston" Colver of murdering Joanne Witt for opposing his relationship with Witt's then-14-year-old daughter, Tylar.
Colver, now 21, and Tylar, now 16, blamed each other
for stabbing Witt 20 times as she was lying in bed in her upscale El Dorado Hills, Calif. home.
Colver's mother, Jan Colver, wept as the Placerville, Calif. jury convicted Colver of first-degree murder and found true the special circumstances of use of a deadly weapon, lying in wait and killing a witness to a crime.
Joanne Witt was murdered two years ago after she complained to police that Colver had committed statutory rape.
The prosecutor, who said the case was about "forbidden love," presented evidence against Colver, including the recovery of male DNA from under Joanne Witt's fingernails and incriminating remarks by Colver, including journal entries.
"It is a true test when faced with the task of taking the life of another to be with the one that you love," Colver allegedly wrote.
Some of the most compelling evidence came in the testimony of Tylar, who claimed Colver committed the murder. Colver also testified, insisting that Tylar killed her own mother, then called him to come over.
Tylar pleaded guilty
to first-degree murder last year under a deal that reduces the conviction to second-degree murder in exchange for her testimony against Colver.