GOLDEN, Colo. (AP) -- Prosecutors say a teenager who allegedly confessed to killing a 10-year-old Colorado girl and attacking a runner also sexually assaulted the girl.
Seventeen-year-old Austin Sigg was charged as an adult with 17 counts in both cases Tuesday. They include four murder charges.
Sigg didn't speak during the brief court hearing in Golden and didn't look at his six relatives in the courtroom that included his mother, Mindy Sigg. His relatives sat silently as the charges were read, unlike the hearing last week where Sigg's mother sobbed audibly.
Eight relatives of Jessica Ridgeway, of Westminster, also watched the proceedings, including her mother. Each wore purple, Jessica's favorite color.
Defense attorneys anticipate asking the judge to send the case to juvenile court. If convicted as an adult, Sigg faces up to life in prison with the possibility of parole after 40 years. If he is tried as a juvenile, Sigg faces a maximum of seven years on each conviction, which, if ordered to be served consecutively, would put him in prison for decades.
In charging documents, prosecutors said Sigg acted alone in kidnapping, robbing, and sexually assaulting Jessica. The robbery charge involved Jessica's backpack and water bottle, which were found in another suburb three days after she disappeared while walking to school Oct. 5.
"Austin Reed Sigg unlawfully and feloniously, acting alone, committed sexual assault, and in the course of or in furtherance of that crime, caused the death of Jessica Ridgeway," according to court documents.
Police arrested Sigg on Oct. 23 after his mother told The Associated Press that she called police and her son turned himself in.
Jessica lived on a quiet street about a mile from where Sigg lived with his mother. The subdivision features an elementary school, a high school, small parks, greenbelts, open space and a lake.
Sigg is being held without bond at a youth correctional facility. The charges filed were four counts of murder, two counts of kidnapping, sexual assault on a child and robbery in Jessica's abduction and slaying as well as attempted murder, attempted sexual assault, and attempted second degree kidnapping in the attack on the runner. Prosecutors also charged Sigg with six counts of crime of violence.
"There's DNA evidence, and the evidence is overwhelming," prosecutor Hal Sargent said at a hearing Thursday, arguing that Sigg should be held without bail despite having no criminal record.
Police said the runner reported being grabbed from behind by a man who placed a rag with a chemical smell over her mouth. Police have not revealed whether the rag was soaked with a chemical meant to subdue the woman.
Former high school classmates painted a picture of the 5-foot-6, 160-pound Sigg as an intelligent teen who often wore black and complained about school but who would stay late sometimes to work on computers. Sigg was interested in mortuary science and was taking forensics classes, according to classmates.
Sigg enrolled in August at Arapahoe Community College, which offers the state's only accredited mortuary science program. The school said Sigg didn't have enough credits yet to apply to that program.
Sigg had left Standley Lake High School in July after finishing the 11th grade and later earned a GED. School officials don't know why he left.
Former schoolmate Sarah Morevec said Sigg had been bullied for having a high voice.