(CBS/AP)-- Austin Sigg, a 17-year-old charged with kidnapping and murdering 10-year-old Colorado girl Jesscia Ridgeway and attacking a runner, will be prosecuted as an adult and also moved to an adult jail cell, a judge said Tuesday.
Sigg was charged as an adult last month. His lawyers had the option of asking to move the case to juvenile court instead, but Judge Stephen Munsinger said that the defense had waived its right to do that.
If convicted as an adult, Sigg faces up to life in prison with the possibility of parole after 40 years. A conviction in juvenile court also could have brought a stiff sentence. He faced a maximum of seven years there on each count, which could have put him in prison for decades if he were ordered to serve his sentences consecutively.
Defense attorneys have not said publicly why they did not seek to move the case to juvenile court.
Jessica disappeared Oct. 5 as she was walking to school in the west Denver suburb of Westminster. Sigg is accused of killing her and of attacking a 22-year-old runner, who escaped, in May during a separate incident. Prosecutors say he confessed to both crimes.
During Tuesday's hearing, Munsinger also agreed to move Sigg from a juvenile detention facility to an adult jail at the request of state's juvenile justice system officials. Sigg's lawyers opposed the transfer.
Sigg's next court appearance will be a motions hearing scheduled for Dec. 12. A preliminary hearing, where the judge will decide if there is sufficient evidence to go to trial, is scheduled for Feb. 22.