Teen Pleads Guilty to Killing Colo. School Girl Nearly a year to the day that a 10-year-old girl was grabbed and pulled into a car as she walked to school, a teen who reportedly had a fascination with death is facing the possibility of life in prison after pleading guilty in the case. Austin Sigg, 18, pleaded guilty Tuesday to kidnapping, sexually assaulting and killing Jessica Ridgeway, just two days before his trial was scheduled to begin. He also pleaded guilty to a May 2012 attack on a 22-year-old jogger at a lake at a park, also in the Denver suburb of Westminster. Sigg agreed to plead guilty to all charges without any concessions from prosecutors against the advice of his attorneys. Neither he nor the lawyers explained why during the court hearing but his father, Rob Sigg, later said he was thankful the Ridgeway family would be spared a trial. Sigg would be eligible for parole after serving 40 years in prison on the first-degree murder charge he pleaded guilty to. Prosecutors want Judge Stephen Munsinger to impose consecutive sentences on some of the other charges involving Jessica so Sigg spends the rest of his life behind bars. Sigg glanced at his family seated on his side of the courtroom as he entered and only spoke to answer the judge's questions about whether he understood what he was pleading guilty to. Jessica's mother, father and other relatives, many of them dressed in Jessica's favorite color, purple, sat on the other side. Her mother, Sarah Ridgeway, briefly left the court as a prosecutor described how Sigg saw Jessica walking to school, grabbed her, tied her hands and feet together, and strangled her. Her father, Jeremiah Bryant of Missouri, sat in the row behind her. After the hearing, Jefferson County District Attorney Peter Weir, flanked by the prosecution team and local, state and federal law enforcement officials, said he believed Sigg pleaded guilty because of the strong evidence against him. "Austin Sigg has been brought to justice but most importantly this case has been about justice for Jessica," he said. Jessica, a fifth-grader who was a member of a peewee cheerleading squad and looking forward to being a zombie lifeguard for Halloween, left home to walk to school on Oct. 5, 2012. Mailboxes and trees were encircled by ribbons in purple. He also allegedly told investigators that he dismembered Jessica in a bathtub. Sigg dropped out of high school after the 11th grade and later earned a graduate equivalency diploma. Former classmates say he was intelligent, interested in mortuary science and was bullied for having a high voice. When asked about his criminal record on the 911 call, Sigg told the dispatcher: "The only other thing that I have done was the Ketner Lake incident where the woman got attacked. That was me. In the attack on the jogger, investigator Michael Lynch testified that Sigg used homemade chloroform to attempt to subdue the woman. She escaped.