Oregon ? A 13-year-old girl convicted of attempting to kill two classmates by slipping rat poison into their milk was sentenced to up to 12 years in a juvenile detention center.

Holley Sweeney was ordered Friday to remain at the Hillcrest Girls’ School in Salem until she is 25 with early release possible if she responds to treatment, the judge ruled.

Earlier this month, the judge found the Lakeview girl and her friend, Stephanie Quesnoy, 12, guilty of plotting and executing a plan to kill two classmates they disliked. Quesnoy is to be sentenced May 22.

The girls put d-Con rat poison in the milk of two classmates Sept. 19 during lunch at Daly Middle School. The victims noticed green crystalline pellets in the bottom of their milk cartons and neither was injured.