Weili Kao was already serving a 16-year prison term for choking her 6-year-old stepdaughter, knocking her to the ground and putting her in a coma in 2004.
But her sentence was converted to 15 years to life this week after she entered a no-contest plea Dec. 3 to a new case of second-degree murder following the girl's death in 2010.
Sacramento Superior Court Judge Patrick Marlette imposed the term Wednesday. Kao, 43, had assaulted her stepdaughter Truly Lo on May 11, 2004, in their Lanfranco Circle home in North Natomas. The girl never regained consciousness.
"It is too much for everyone in the family to take," Thomas Lo said in a letter to the court about the death of his daughter, who "had such a tender heart."
Kao told authorities she hit and choked Truly in a closet while disciplining the girl for pushing down her younger, 16-month-old sister.
According to police and probation reports, Kao had ordered the girl to stand up during a timeout. She became enraged when Truly didn't follow her instructions and instead lay down, the reports said.
"It's particularly hard to set aside thoughts of how scared Truly undoubtedly was in that closet that night," Deputy District Attorney Valerie Brown said Thursday. "Justice requires that the defendant spend the rest of her life behind bars for her atrocious acts of violence."
Defense attorney Charles Bauer said Kao was newly pregnant at the time she hit and choked Truly. He said Kao was further stressed because the family had just moved to the Sacramento area but her husband still worked in the Bay Area. He would leave for work on Monday mornings and not return until Friday evenings, Bauer said.
"I think it was just one of those things where she got overstressed and overburdened," he said. "She basically had it to her limit."
A probation report from Kao's 2005 child abuse conviction quoted a psychologist's report as saying the woman suffered from postpartum depression and post-traumatic stress disorder from a troubled childhood in Taiwan.
The report said that an "underlying personality disorder characterized by paranoid dependent and obsessive compulsive features" in Kao also was "strongly suggested."