A teenager charged with fatally shooting a classmate in a school cafeteria in Knoxville, Tenn., will be tried as an adult.

A juvenile court judge ruled Wednesday that 15-year-old Jamar Siler's case will be moved to adult court, where Siler could face life in prison if convicted of first-degree murder. He is charged in the death last August of 15-year-old Ryan McDonald. In juvenile court, the maximum is incarceration until 19.

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The Knoxville News Sentinel reported that Irwin found probable cause to believe Siler committed the crime. The newspaper also said the judge set Siler's bond at $500,000, noting Siler escaped for a few hours from a juvenile detention center last month before being captured.

Authorities have not disclosed a motive for the shooting.