KEALAKEKUA, Kona — A Big Island judge has revoked probation and jailed an 18-year-old woman who admitted to stabbing her infant son to death in 2005.

Kona Circuit Judge Elizabeth Strance also set a new sentencing date for Julia Lewis, a hearing where Lewis will face the possibility of up to 20 years in prison for the slaying.

Lewis was 16 when she was charged with second-degree murder for the Oct. 12, 2005, stabbing of her infant son, Sebastian Randall Kossak, who died of wounds to his neck. Lewis pleaded guilty to a lesser manslaughter charge last year, telling the court she suffers from depression and a bipolar disorder.

Under terms of the plea agreement, Lewis was to receive a sentence of up to one year in jail, 10 years' probation and restriction to a secure Mainland mental-health treatment facility until she is 21.

That deal unraveled in Circuit Court Friday after mental facilities on the Mainland refused to accept Lewis, and the Kahi Mohala adolescent treatment program where she had been held on O'ahu would not take her back because she is now too old for that program.

Strance said she never would have accepted the plea agreement without the assurance that Lewis would be held in a locked treatment facility until she is 21.

After listening to testimony on state efforts to place Lewis on the Mainland, Strance said it "seems to me evident" that Lewis worked independently or with her mother, Sharon Lewis, to "sabotage" efforts to find an appropriate institution.

Strance ruled that Julia Lewis had violated the terms of her probation by failing to enter a secure Mainland treatment facility.

Lewis testified that she would have gone to a California facility the state had proposed for her, but acknowledged she did write a letter arguing that the program was "not appropriate for her." Among other issues, Lewis was concerned there were male sex offenders housed at the facility.

The California program later rejected Julia Lewis after Sharon Lewis called the vice president of the program and raised "issues she had concerns over," according to testimony from Lewis' probation officer.

Sharon Lewis said she was looking out for her daughter's interests when she called the California institution because she was worried her daughter could be physically or sexually abused at the facility.

Sharon Lewis denied she ever sabotaged efforts to place her daughter in a Mainland treatment facility, and said state officials haven't done enough to get Julia appropriate treatment.

"I'm the big bad guy because I tried to look out for my daughter, and I just don't understand this system, I really don't," she said. "They want me to go away, they want me to be quiet, they want me to just shut up and let their system work, but their system doesn't work.

"It's ludicrous that they're saying that they've done the best they can for her, when in fact they have not," Sharon Lewis said. She added that she intends to look herself for an appropriate placement for her daughter.

Lewis said she is a psychiatric nurse, and said Julia's child was killed when Julia suffered a postpartum psychotic episode that lasted for about five months. Sharon Lewis said her daughter has never been in trouble before, and that Julia misses the baby.

Deputy Prosecutor Cynthia Tai, however, cited during the courtroom argument a recent mental evaluation that found Lewis remains at "high risk" for violence to herself or others.

Strance set bail for Lewis at $200,000, and set her re-sentencing for Aug. 10.

Tai said she intends to ask for a 20-year prison sentence for Lewis, but Strance also could re-sentence Lewis to probation if an appropriate secure mental-health facility can be found.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.