The mother told the investigator that, because it was drizzling that morning, she had arranged for Jessica to walk to a male student's nearby home and the boy's father would drive them to school.
Lopez said the boy's home was only two-tenths of a mile away, but Jessica never made it there. The father of the boy waited for a while, but when the girl didn't arrive, he drove his son to school.
Lopez also testified that an autopsy showed Jessica died from asphyxiation due to strangulation or suffocation.
Her partial remains were found when two men collecting litter in an open space field came across a shiny black plastic bag, indicating it hadn't been exposed to the elements for too long, the detective said.
The men opened the bag and found another plastic bag inside, Lopez said. The interior bag was heavy and "didn’t feel right," so the men called a supervisor and police were soon alerted, Lopez added.
Lopez said the bag contained the girl's torso, which was missing her arms, legs and head. The rest of the remains were found in the crawl space of Sigg's Westminster family home, the detective said.
Sigg's mother, Mindy Sigg, called police after the teen went to her with "disturbing information," a relative revealed after his arrest last May.