Alameda County Superior Court Judge C. Don Clay said the evidence indicates that Taquan Maldonaldo abused 26-year-old Katrina Moore over a period of time and was high on drugs when he killed her at her home in the 2100 block of Eden Canyon Road in Castro Valley on June 5, 2010.
"These drugs are evil and that was the accelerant in this case," Clay said.
The judge said Moore "was just too young to die."
Moore's father, 62-year-old Robert Spinardi, said she was "an innocent person who had her life snatched away from her.
Spinardi said Moore "loved people" but "never developed a defense mechanism to sense the bad in the people around her because she always saw the good in people."
He said his daughter worked as a beautician but became a methamphetamine addict after being exposed to the drug by people she shared a house with.
Spinardi said Moore kicked her habit at one point and got married and had a son, but eventually she relapsed and she and her husband had their son taken away by Alameda County's child protective services agency.
He said Moore met Maldonaldo after she and her husband separated.
Spinardi said, "At first I thought Taquan was a decent guy but when she started showing up at my house with black eyes, I changed my opinion."
He said Moore tried to break up with Maldonaldo but "she waited too long" and "he wouldn't let her go."
Moore was planning to move to Sacramento to reunite with her husband and try to get their son back but Maldonaldo killed her shortly before that could happen, Spinardi said.
Spinardi noted that Maldonaldo has two daughters from another relationship and asked Maldonaldo, "How would you feel toward a man who murdered your daughter?"
He said he's particularly upset that Maldonaldo tried to cover up his crime by hiding the knife and delayed calling police after he stabbed Moore.
"It was a survivable wound but she bled to death under your total control," Spinardi said.
Maldonaldo told police that Moore suffered her fatal injury after he had picked her up while kissing her, tripped over a laundry basket and fell into a glass sliding door.
But Clay said Maldonaldo "told a story that the jury didn't believe."
Before he was sentenced, Maldonaldo said, "I want the family to know I'm very sorry."
Clay said, "I truly believe he is remorseful for what he has done."
The judge said, "I really don't think Mr. Maldonaldo is an evil person. But I do think he was an evil person that day."