Sacramento police described the crime as "unimaginable," one that likely will haunt a family, a neighborhood and the team of detectives investigating it for some time to come.
At the heart of the horrific case is 9-year-old Matthew Raymond Hernandez, who was slain with a hatchet in his family's South Natomas home late Tuesday night.
Accused in his killing is his father, 36-year-old Phillip Raymond Hernandez, who was arrested a short time after the gruesome discovery.
Even with a suspect in custody, police, like the community, continued to search Wednesday for an explanation that so far is elusive.
"So many questions of 'Why?' " said Sacramento Police Officer Michele Gigante, a department spokeswoman. "It's just horrible."
The incident began before midnight Tuesday, when Sacramento police received two 911 phone calls from a home in the 2200 block of Atrisco Circle. They arrived to find the boy dead with severe trauma.
Officers flooded the neighborhood, and soon found the elder Hernandez about a mile away, walking near Azevedo Drive and El Camino Avenue.
According to the police account, Phillip Hernandez went into the backyard earlier that night to get a hatchet and, for unknown reasons, broke through a sliding glass door to get back inside.
An elderly woman who lives in the home described by neighbors as the boy's great-grandmother heard the glass shatter and ran to the living room, where she found Hernandez armed with a hatchet and standing over his sleeping son, Gigante said.
The woman tried to intervene, but the elder Hernandez thrust her aside and began to attack 9-year-old Matthew with the hatchet, Gigante said. The elderly woman witnessed the violence.
Matthew's 12-year-old brother was home at the time but was not injured.
The boys' mother, Jessica Hernandez, lives out of state and was headed to the Sacramento area Wednesday as the man accused of killing her younger son remained at the Sacramento County Main Jail.
From the jail's psychiatric floor, Phillip Hernandez declined to be interviewed by the media. He is scheduled to be arraigned Friday.
Criminal and family court records document a turbulent history replete with domestic violence and a bitter custody battle between him and the mother of his children.
According to child custody paperwork, the couple married in January 2001 but separated in April 2004. Three months later, Phillip Hernandez was charged with corporal injury on a spouse and attempted kidnapping, both felonies, Sacramento Superior Court records show. The latter charge was dismissed, but Hernandez ultimately pleaded no contest to the domestic violence charge.
He was sentenced to 120 days in jail and five years of formal probation, records show.
Phillip Hernandez violated the terms of that probation in November 2005, when he was again charged with corporal injury on a spouse this time in Yolo County. He was convicted of the charge and was sent to prison.
Records from the California Department of Corrections and Rehabilitation show Hernandez served time from July 2006 to October 2007. He was discharged from parole in November 2008.
Meanwhile, Jessica Hernandez had custody of the couple's two children. After Phillip Hernandez's release from prison, the two fought over that issue, and ultimately the court imposed an arrangement upon them, family court records show. The children would stay with their mother during the summer, their father the rest of the year, and at alternating homes during holidays.
That arrangement was ordered last October. They were scheduled to return to court July 1 for a "review of parenting, mother's child care and school plans, status of father and his girlfriend and grandmother moving," records show.
Neighbors on Atrisco Circle said Hernandez, his children and his grandmother had not lived in the home long. Public records indicate they might have moved from Southern California.
Karen Hardy, who lives nearby, said her daughter sometimes rode bikes with Matthew. As they set off for school Wednesday morning, Hardy said she had to delicately explain why there were so many police cars in the neighborhood.
When she told them the boy's father was thought to be responsible, Hardy said her son and daughter wondered: "What is wrong with that guy?"
"It's just really sad," Hardy said from the doorstep of her home.
Hardy said her kids talked a little about the tragedy, but seemed shocked, and stayed mostly quiet during the drive.
"It's just crazy when it hits so close to home," Hardy said.
Less than a mile away at Jefferson Elementary School, where Matthew was a fourth-grader, counselors, psychologists and chaplains gathered to help anyone in need. School staff members called families to alert them that they could get support at the school, if needed.
The Natomas Unified School District released a statement that said, in part: "We are deeply saddened by the tragic death of one of our students in fourth grade. Our hearts go out to the family and friends."
Reached Wednesday, Jessica Hernandez's brother declined an interview. Attempts to reach her other relatives, and those of Phillip Hernandez, were not successful.
Gigante said the family is "distraught and traumatized," and investigators are also deeply affected.
"I can see how horrific the scene must have been by how the detectives are responding. As a parent, I couldn't even imagine it," Gigante said. "You don't want to envision it in your mind."