HILO, Hawai'i — Prosecutors have asked a Kona judge to revoke probation for a teenager who pleaded guilty to manslaughter for stabbing her 4-month-old son to death nearly two years ago.

Authorities have been unable to place Julia Lewis, 18, in an appropriate mental health facility, and placement in a secure facility until Lewis reaches age 21 was required when she was sentenced to probation last year, said Deputy Prosecutor Cynthia Tai.

If Lewis' probation is revoked and she is resentenced, she faces a prison term of up to 20 years for the manslaughter conviction.

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.

The child was killed in Lewis' family home on 'Olu'olu Street in the Kona Highlands Subdivision, and police were initially told the stabbing was "accidental."

When Lewis pleaded guilty to the lesser manslaughter charge last year, she told 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 Mainland therapeutic institution until she is 21.

Last September, Judge Elizabeth Strance approved that plan, sentencing Lewis to one year of jail time and 10 years of probation. However, Strance gave Lewis credit for the nine months she had been confined to the Kahi Mohala mental health facility on O'ahu, and suspended three months of jail time.

The plan at the time was to house Lewis in a South Salt Lake, Utah, facility until her 21st birthday, and then return her to Hawai'i to complete the balance of her probation.

That never happened, Tai said. Instead, Lewis was rejected by treatment facilities in several states, and she has remained at a treatment facility on O'ahu. Tai declined to say why the facilities would not accept Lewis.

The Department of Health has been trying to place Lewis in a facility that will get her the treatment she needs, but if that isn't possible, Tai said prosecutors will ask that she go to prison. At a hearing last week in Kona, state officials reported they have identified another facility that may accept Lewis, and Strance delayed ruling on the request to revoke Lewis' probation until June 15.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.