The Jefferson County, Colo., district attorney said he would try a 17-year-old boy as an adult in the kidnapping and slaying of 10-year-old Jessica Ridgeway. The teen was scheduled to appear in Jefferson County court Thursday where he will be advised he is being held on suspicion of first-degree murder, felony murder and kidnapping, in addition to suspicion of criminal attempt to kidnap and murder in a separate attack on a jogger at Ketner Lake in May, The Denver Post said. Due to precedence in previous U.S. Supreme Court rulings, 17-year-old Austin Sigg would not be eligible for the death penalty or a mandatory life term without parole if convicted, District Attorney Scott Storey said. Police arrested Sigg Tuesday at his home less than a mile from the Ridgeway home after his mother called authorities, the Post reported. Fellow classmates of Sigg said he majored in mortuary science at Arapahoe Community College and was interested in forensic science. \"He said he was intrigued by dead bodies,\" said classmate Jacqueline Miller. \"There was something creepy about him.\" Jessica disappeared from her Westminster home Oct. 5 when she left for school. Five days later, her body was found dismembered in a bag at a park in Arvada, several miles from her home.