Sigg faces 17 charges, including four counts of first-degree murder, two counts of second-degree kidnapping, sexual assault on a child and robbery in connection with Jessica's disappearance and subsequent murder. He is also charged with three counts of crime of violence for Jessica's murder. The crime of violence charges stem of Jessica's abduction, injury and eventual death.
"In addition to traditional after-deliberation murder, Sigg has been charged with three counts of felony murder," 9NEWS Legal Expert Scott Robinson said. "That is based on a death occurring during the commission of one of three separate felonies: robbery, sexual assault and kidnapping. That's first-degree murder - just another type of the same crime."
Jessica disappeared Oct. 5 after leaving her home to meet a friend for a walk to school. Her house is about a mile from where Sigg lived with his mother.
Police received a phone call from Sigg's mother last week, and that's what led to his arrest.
"Anyone who is convicted of killing and dismembering a child has very little chance of ever seeing the light outside of the prison walls," Robinson said.
Sigg is also charged with one count of first-degree attempted murder, one count of second-degree kidnapping and one count of attempted sexual assault in connection with the Ketner Lake incident. He is also charged with three counts of crime of violence.
"It's not the number of charges that have to be difficult for Sigg, it's the seriousness," Robinson said. "In addition to having to spend at least 40 calendar years in prison, if Sigg is convicted of any of the charges involving the Ketner Reservoir crime, then those ... can be consecutive time on top of that."
In that attempted-abduction case, a woman reported a man grabbed her from behind and placed a rag over her mouth that had a chemical smell over Memorial Day weekend. She was able to escape the attacker.
The crime of violence charges against Sigg stem from Sigg allegedly using a deadly weapon - in this case a chemical mixture - to attempt to kidnap the victim. It also includes his alleged use of force against the victim.
Sigg's next court appearance is Nov. 27 at 11 a.m. The defense team has seven days to file a request to reverse the ruling to send Sigg to adult court.
"The prosecution has an absolute right to direct file this case," Robinson said. "Now, the public defenders have the right to ask for the case to be transferred back to juvenile court, but the factors that govern is called a 'reversed-transfer hearing' are strongly in favor of the case remaining in adult court. They include the seriousness of the offense, the impact of the offense on the victim and whether society as a whole, the community would require greater punishment than seven years in a juvenile facility. It looks like to me almost no chance that this case will be reverse transferred back to juvenile court."
Currently, Sigg is being held in a juvenile facility. He is expected to be eventually transferred to the adult jail. A judge will have to decide that.
Interactive timeline of the case:
(KUSA-TV © 2012 Multimedia Holdings Corporation with The Associated Press)