A 12-year-old boy accused of fatally stabbing his 8-year-old sister appeared in juvenile court to face murder charges on Wednesday.

The boy was formally charged with second-degree murder in the death of his sister, Leila Fowler. No plea was entered in the brief hearing, NBC station KCRA reported.

The small town of Valley Springs, Calif., is reeling after authorities made an arrest in the killing of 8-year-old Leila Fowler: her 12-year-old brother, who previously said a man broke into their house and killed his sister. NBC's Amna Nawaz reports.

Leila Fowler’s death and the boy’s report that an intruder was responsible triggered a two-week manhunt that struck fear into the rural Northern California town of Valley Springs some 60 miles south of Sacramento.

Mark Reichel, an attorney hired by the Fowler family, told The Associated Press after the hearing 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," Reichel said.

Reichel earlier told NBC station KCRA that just because the boy lied doesn’t make him a killer.

Under California law, if the boy is found to have committed the crime, he could be imprisoned until he is 25 years old.

The boy told investigators April 27 — the day of his sister’s death — that he had encountered a random attacker, a tall man with long gray hair, in the family home while his father was away at a Little League baseball game.

He said that he startled the man, who fled on foot. The boy said that he then found his sister bleeding.

The girl’s death and the prospect of killer on the loose frightened residents of the Valley Springs and set off a manhunt, with officers going door to door in search for the attacker.

The Calaveras County Sheriff's Office said they spent more than 2,000 man-hours amassing evidence and searching for the man. Some residents even called in reports of seeing a man that fit the description.

Thousands attended a candlelight vigil in Leila's honor.

After the boy’s arrest on Saturday, his father, Barney Fowler, said that he is backing his son.

"Until they have the proper evidence to show it's my son, we're standing behind him," Fowler told the Associated Press. "If they have the evidence, well, that's another story. We're an honest family."

NBC News is not naming the suspect because he is a minor.

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Boy, 12, charged with second-degree murder in 8-year-old sister's stabbing death