An Orange County jury Thursday convicted a 23-year-old Huntington Beach man of first-degree murder in the stabbing death of his girlfriend's mother.
Ian W. Allen faces 25 years to life in prison.
Barbara Mullenix, 56, was stabbed and slashed more than 50 times when her then 17-year-old daughter, Rachael Mullenix, conspiring with Allen, attacked her in her Huntington Beach bedroom on Sept. 13, 2006. The daughter was convicted of first-degree murder in July.
The pair, who had been dating for three months after meeting at a party, then stuffed the body in a cardboard television box and dumped it in Newport Harbor.
At Allen's trial, his defense attorney argued that Allen merely tried to cover up the killing after Rachael Mullenix flew into a rage and stabbed her mother, who was characterized during the trials as an out-of-control drinker prone to verbal abuse.
Prosecutor Sonia Balleste portrayed Rachael Mullenix as a spoiled, manipulative girl who lured Allen into the murder plot. Her mother allowed her to date Allen but grounded her when she broke her 1 a.m. curfew.
Balleste said Rachael had grown up unaccustomed to hearing the word "no." Even after she slashed her mother with a knife in Tampa, Fla., in 2004, Barbara Mullenix declined to press charges, according to testimony during the trials.
"She faced no consequences for what she did, so by the time her mother tried to rein her in, it was too late. When she got grounded, it was a motive for murder in her mind," Balleste said. "If there is a message about what happened, it is that parents need to be parents. If you wait too late to do that, you die trying."
The jury in Allen's case deliberated for three days before reaching its verdict. Allen will be sentenced in November; Rachael Mullenix next month.