Tiffany VanAlstyne, the teenager accused of murdering 5-year-old Kenneth White, has pleaded guilty. The plea came in Albany County Court Tuesday morning. Time Warner Cable News' Geoff Redick reports.

ALBANY, N.Y. — For Albany County Sheriff Craig Apple, a surprise plea on Tuesday brought "some closure:" Tiffany VanAlstyne, the 20-year-old accused of strangling her young cousin, admitted to the murder.

Terms of her plea deal mean VanAlstyne will serve 18 years to life in state prison.

"But this was a systematic failure, as far as I'm concerned," says Apple. "I firmly believe that this was a preventable death."

Five-year-old Kenneth White died on December 18 last year, when VanAlstyne now admits she choked the boy to death inside their Town of Knox trailer home. She then buried his body in a snowbank across the street. In a panic, VanAlstyne reported White kidnapped and set off a manhunt that only ended when authorities discovered the boy's battered body.

The murder touched off a months-long Family Court battle that uncovered a history of physical abuse in the home Kenneth and Tiffany shared with Kenneth's younger sisters, Tiffany's mother Brenda, and several others. Following Kenneth's death, his four- and five-year-old sisters were placed in foster care; a judge would later declare the family's home unfit for children. The girls remain in foster care.

Apple says the county's Department of Child and Family Services, along with Child Protective Services, should have diagnosed those problems much sooner.

"Young girls and a young boy were being beaten a lot (in that home)," Apple said. "These kids were supposed to be taken care of ... and basically, that was nothing more than Satan's house."

The sheriff has worked to bring publicity to the case and the problems it exposed in the CPS system. Monday, one day before the surprise plea deal, Apple was part of a news conference announcing a new statewide law, which quickens police access to CPS records in the event of an emergency like Kenneth White's.

Others on Monday were pleased with the plea deal. Kenneth's Army, a child advocacy group formed in the wake of White's murder, called the agreement "justice."

"I don't think it's really a 'victory' ... this young girl, with problems of her own, has lost her life as well," said Michelle Fusco, a founding member of Kenneth's Army who has attended most of the Family Court appearances for Kenneth's family.

Fusco and others in the group have purchased a headstone for Kenneth, placed a memorial where his body was found, and organized a college scholarship in Kenneth's name for students at Berne-Knox-Westerlo High School.

The group also donates money to a fund for Kenneth's sisters, set up by Sheriff Apple.

"We will never stop making sure this boy is never forgotten, that he has not died in vain," Fusco said Tuesday.