A 12-year-old boy charged in the stabbing death of his sister, Leila Fowler, 8, appeared in Calaveras County Superior Court on Wednesday but did not enter a plea.
The District Attorney's Office is charging him with second-degree murder with a special allegation for use of a dangerous weapon. Second-degree murder indicates the killing was not premeditated.
The boy's arraignment was continued until May 29 to give defense attorneys Mark Reichel and Steve Plesser, of Sacramento, time to review evidence, Reichel said.
"We have questions," Plesser said after the hearing. "Why do the police think the minor did this? Why would a 12-year-old commit an offense like this? And how did it not lead to an immediate arrest and it took 2,000 hours of resources by the Sheriff's Office and the FBI? We're confident we'll get the answers when we examine and test the evidence."
The court will also hold a juvenile detention hearing to determine if the boy must remain in custody.
He is being held at a juvenile detention center in El Dorado County and is not able to post bail before the hearing, Reichel said.
The defense attorneys asked the court to close Wednesday's hearing because it is a juvenile case, which would typically be confidential, but Judge John E. Martin denied the request, Reichel said.
California law does not have a provision for trying minors under age 14 as adults.
If adjudicated a delinquent - the juvenile court equivalent of being found guilty - the boy can only serve time until age 25, according to legal experts.
During a brief statement made to the public after the hearing, Plesser questioned the boy's maturity.
"Can a 12-year-old be psychologically, intellectually and emotionally mature enough to aid attorneys in defending himself against the most serious of charges?" Plesser asked.
Calaveras County Sheriff's Office detectives arrested Leila's 12-year-old biological brother at 5:10 p.m. Saturday at the Valley Springs substation, following a two-week investigation. He was booked on a charge of murder.
Leila was found with multiple stab wounds in her home on the 5600 block of Rippon Road in Valley Springs on April 27.
Father Barney Fowler and his fiancee, Crystal Walters, were at a baseball game nearby.
Walters dialed 911 about noon after receiving a call from the 12-year-old boy, who was home alone with Leila, saying an intruder was in the home.
Leila was taken by ambulance to Mark Twain Medical Center where she was pronounced dead about 1 p.m.
Barney Fowler attended the hearing with Walters. Also in attendance was the kids' biological mother, Priscilla Rodriguez.
Reichel told the public that the family wants to be left alone.
"As they travel down this incredibly difficult path, they are obviously extremely concerned about their son, who they also dearly love," he said. "I'm sure every family in America can understand they are going through extremely difficult times. This is a good family."
The Associated Press contributed to this report.