Youngest Sister Sentenced to Youth Authority for 1991 Murder of Neighbor : Courts: Three teen-age girls took part in the brutal stabbing of a woman who had befriended them. Their motive remains unknown.

A 14-year-old girl, youngest of three teen-age sisters from Northridge convicted of murdering a neighbor woman who befriended them, was sentenced Thursday to the California Youth Authority.

Rejecting arguments that the girl was not as culpable as her two older sisters, San Fernando Valley Juvenile Court Commissioner Antoinette Liewen sentenced her to 15 years to life in the youth authority’s custody for second-degree murder. Despite the sentence, she will serve no longer than 11 years, because under state law CYA prisoners must be released by their 25th birthday.

The girl’s attorney, Jerome V. Posell, argued unsuccessfully that the teen-ager should be sentenced to a short-term youth camp instead of the CYA because she had been coerced by threats from her older sisters, aged 16 and 18, into participating in the murder.

The older sisters were sentenced earlier to the CYA after being convicted of first-degree murder for the 1991 stabbing of Meta Francis Murphy, 62.

Posell also had argued that a psychiatric evaluation of the girl indicated that she had been suffering from depression before and after the murder after years of physical and psychological abuse from her stepfather and sisters.

But Deputy Dist. Atty. Thomas Rubinson countered with a school evaluation of the girl made after the slaying indicating that, although she had a learning disability, she was a “pleasant and cooperative student.”

“There was no evidence that the minor was withdrawn or depressed,” said Kenneth Jones, a psychologist with the Los Angeles Unified School District who serves as a liaison to the court.

While noting that the girl came from an “extremely dysfunctional family,” Liewen said youth camp was not appropriate for a “very incomprehensible” act with “no real motive.”

“The youth authority will provide psychiatric and educational treatment that she very much needs so that hopefully, when she comes out, she will be able to say no” when someone tries to push her into taking such actions, Liewen said.

Rubinson said he was glad that the case was finally over.

“The entire case is very sad,” he said. “The only thing that isn’t sad is that the girls got caught and were convicted. The community can now breathe a sigh of relief.”

The murder shocked neighbors in the quiet condominium complex on Mayall Street in Northridge, where Murphy, a librarian who lived alone, was a neighbor of the sisters’ family. She had often cared for the girls’ pet cats. Investigators and those who knew the sisters and the victim were especially horrified that the girls never offered a reason for the killing.

According to testimony, while the oldest sister remained at home to turn up the volume on two stereos to drown out noise, the 16-year-old hit Murphy over the head with a lamp and struggled with her. When the 16-year-old shouted for help, the 14-year-old handed her a knife and the 16-year-old stabbed Murphy 11 times, prosecutors said.

Murphy’s body was then dumped in a closet and covered with coats.

The murder remained a mystery for several months, until an acquaintance of the girls told police that she heard the two older sisters bragging about the killing.