Judge Stephen Munsinger granted the request and postponed the arraignment of Austin Sigg until April 12.
The 18-year-old suspect is charged with the murder, kidnapping and sexual assault of Jessica Ridgeway. The fifth-grader's disappearance last fall sparked a massive manhunt and fear among residents of Denver's west suburbs.
Police have said Sigg acknowledged during questioning that he strangled Jessica then dismembered her body in a bathtub at his mother's home. The child's remains were found in a park and in a crawl space at the home.
On Tuesday, defense attorney Katherine Spengler said Sigg's legal team also needed to study the massive amount of evidence in the case and analyze his mental state at the time of the crime.
"A race to justice really is no justice at all," Spengler told the judge.
Sigg wore an orange jumpsuit in court, where he flashed a tight smile and talked with his attorneys before the hearing.
Jessica's mother, Sarah Ridgeway, and other supporters in the audience wore purple—Jessica's favorite color—at the hearing.
Police have said Sigg vehemently denied sexually assaulting Jessica.
Jessica lived in suburban Westminster with her mother, about a mile from Sigg's home. Her father, Jeremiah Bryant, lives in the Kansas City suburb of Independence, Mo.
Jessica disappeared Oct. 5 while walking to meet a friend just two blocks away on their way to school.
Her body was found on Oct. 10 along a remote road in a park. Police scoured her neighborhood and even collected cheek swabs for DNA from some residents.
Authorities asked the public to keep an eye out for people exhibiting unusual behavior such as leaving town unexpectedly, missing appointments or changing their appearance.
On Oct. 23, Sigg's mother, Mindy Sigg, called 911 to say her son wanted to turn himself in. When the dispatcher asked what her son had said, she replied, "That he did it, and he gave me details, and her remains are in my house."
Her son then spoke with the dispatcher.
"I don't exactly get why you're asking me these questions. I murdered Jessica Ridgeway. I have proof that I did it," Austin Sigg said, according to a police recording of the call.
Westminster police Detective Michael Lynch testified at a preliminary hearing that Sigg told his mother that he kidnapped Jessica as she walked past his car, bound her arms and her legs, and took her to his house.
Former classmates said the 5-foot-6, 160-pound Sigg was intelligent, often wore black, and would stay late sometimes to work on computers. He was interested in mortuary science and was taking forensics classes, they said.
Sigg left Standley Lake High School in July after finishing the 11th grade and later earned a GED. School officials said they didn't know why he left. One former classmate, Sarah Morevec, said he had been bullied for having a high voice.
Sigg cannot face the death penalty because he was 17 at the time of the slaying. If convicted, he could face life in prison with the possibility of parole after 40 years.
He also faces an attempted kidnapping charge involving an attack on a 22-year-old woman who was running near the elementary school attended by Jessica.
Associated Press writer P. Solomon Banda contributed to this report.