Sigg wore a blue-green jail uniform and had a light goatee when he appeared in a heavily guarded courtroom in Golden.
Four of his family members were seated in the court, and they sobbed at times during the hearing.
When District Judge Ann Gail Meinster asked Sigg if a parent was present, he said ‘‘Yes’’ and looked toward his relatives. He then mostly sat with his head bowed.
Seven of Jessica’s family members sat in the courtroom with their arms around each other. Sigg glanced in their direction just once.
Public defender Ryan Loewer had argued for setting bail for Sigg, saying he has no prior criminal history. Prosecutor Hal Sargent said Sigg had confessed and investigators had a strong case.
‘‘There’s DNA evidence, and the evidence is overwhelming,’’ he said.
After the hearing, Jefferson County District Attorney Scott Storey said prosecutors cannot seek the death penalty for Sigg because he is a minor.
Storey said the law is unclear on whether Sigg could be sentenced to life in prison.
The U.S. Supreme Court ruled in 2005 that the death penalty was unconstitutional for minors. Colorado law allows for life sentences for juveniles convicted of serious crimes, but it would be up to a judge to determine whether that’s appropriate, Storey said.
Storey declined to discuss the possibility that Sigg might enter an insanity plea.
Former high school classmates painted a picture of Sigg as an intelligent teen who often wore black and complained about school but who would stay late sometimes to work on computers. Sigg was interested in mortuary science and was taking forensics classes, said Rachel Bradley, 17, who attended Standley Lake High School with him.
Sigg enrolled in August at Arapahoe Community College, which offers the state’s only accredited mortuary science program. He didn’t have enough credits yet to apply to that program.
Sigg had left Standley Lake High in July after finishing the 11th grade and later earned a GED. School officials don’t know why he left.
Former schoolmate Sarah Morevec said Sigg had been bullied for having a high voice.
Noveck contributed from New York. Associated Press writers Dan Elliott and Kristen Wyatt in Denver contributed to this report.