(ABC NEWS) -- The 17-year-old boy arrested in connection to the abduction, murder and dismemberment of 10-year-old Jessica Ridgeway confessed to his mother, who then called police in Colorado so her son could turn himself in, sources said.
Austin Reed Sigg was arrested Wednesday on suspicion of two counts of first-degree murder, one count of second-degree kidnapping and two counts of criminal attempts.
The charges against Sigg are for Jessica's death and for the alleged attempted abduction of a jogger in May 2012.
Sigg will appear in Jefferson County Court later this morning for his initial appearance. The district attorney says he plans on charging Sigg as an adult.
Investigators scoured the Westminster, Colo., home overnight where Sigg lives with his mother. FBI agents combed the backyard for clues and towed away his car.
"He was always egotistical, but I never thought he would go this far," Austin Cassie, who has known Sigg since elementary school, said. "I mean, he wasn't ever that violent of a person. He was more bark than bite."
Sigg is a student at Arapahoe Community College Littleton, Colo., according to his arrest report, where classmates said he was studying mortuary science. He took second place in a high school competition involving crime-scene investigations.
"It's not uncommon for people who abduct women to be fascinated by crime and crime detection, whether it be crime-scene investigation or medical examination or autopsy," former FBI agent and ABC News consultant Brad Garrett said.
Authorities are also studying a 2009 YouTube video briefly showing a boy who resembles Sigg wearing a small cross. It appears similar to the one police say they found at the crime scene in an Arvada, Colo., park, miles from where Jessica was abducted.
Jessica vanished Oct. 5 when she left for school. Her body was found five days later in Arvada. Sigg lives less than a mile from her home and about a half a mile from her school.
Sigg also lives close to a reservoir where he allegedly attempted to abduct a 22-year-old female jogger May 28. Police said a man tried to grab her from behind on a trail around Ketner Lake. The woman said the man tried to put a rag over her mouth that had a chemical smell. She was able to get away and call 911.
Authorities said Tuesday there was a "definitive link" between Jessica's case and the attempted abduction of a jogger.
With a suspect now under arrest, people in Jessica's community hope their nightmare is over.
"I'm scared to walk around my own neighborhood and it's terrifying," Loren Olmstead said Wednesday while fighting back tears. "I don't know why somebody could do this to someone else."
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