Austin Sigg, Colo. teen, gets life for murder of 10-year-old Jessica Ridgeway

(CBS) - The teen who killed and dismembered 10-year-old Jessica Ridgeway was sentenced to life in prison Tuesday.

PICTURES: Body of 10-year-old Colo. girl found

Austin Sigg, 18, pleaded guilty to killing and dismembering Ridgeway in October 2012. Sigg's defense pointed to a recent Supreme Court decision calling mandatory life without parole for juveniles unconstitutional in asking the judge to allow Sigg the possibility of being released someday. Sigg was 17 when he kidnapped and killed Ridgeway.The Associated Press reports that Sigg could have been eligible for parole in 40 years, but the fact that he received sentences on separate charges he had pleaded guilty to eliminated that possibility.

The sentencing phase of the trial took place over two days. Sigg sat expressionless as he listened to an expert psychologist call him "sadistic" and a "necrophiliac," but appeared to weep as Ridgeway's family described the young girl and played a video featuring her photographs.

Sigg kidnapped Ridgeway on her way to school on Oct. 5, 2012. A massive search failed to locate the little girl and it wasn't until Sigg's mother came forward on Oct. 23 to tell police that her son had confessed to killing her that Ridgeway's body was found. And once it was found, it became clear that Sigg had taken Ridgeway into his bedroom, dressed her in new clothes, cut her hair and strangled her, reports the Denver Post. Then, he reportedly dismembered her body and kept parts of it, including her skull. Her torso was found in a field.

Dr. Anna Salter told the court that Sigg may have been aroused by the dismemberment. She said that in 2008, when he was 12, Sigg's family had discovered him watching violent pornography and sought treatment for him.

Sigg's attorney told the court that Sigg was taken to "Christian counseling" where he told counselors he was concerned the pornography was "affecting my whole life." She also said that Sigg was diagnosed with anxiety and obsessive-compulsive disorder and put on medication at age 14.

Sigg's attorney told the court that according to medical records Sigg's mother told doctors that she had fallen down stairs while pregnant, and "breathed some strong paint fumes." She said that the labor was "complicated" and a vacuum was needed to deliver him. She also discussed an intestinal condition that required hospitalization when he was an infant, and his family history of mental health issues.

Dr. Salter testified that, although he committed the murder as a juvenile, the crime did not meet the markers of typically adolescent crime, including impulsivy and seeking peer approval. Sigg used homemade chloroform to subdue Ridgeway after finding a recipe for the substance on the internet.

Complete coverage of the Jessica Ridgeway case on Crimesider