In some ways, it's the most perplexing kind of mystery.
To many, it had looked as though the Fuentes boys were heading toward happiness.
The scrappy brothers, ages 8, 9 and 10, had started a new school year and were set to begin catechism classes that weekend.
Their father had been making plans to move them back into the South Los Angeles home where they had lived for five years, and where sheets emblazoned with basketballs, footballs, baseballs and — their favorite — soccer balls, were still neatly tucked into their bunk beds.
Now the mystery is: What dark inner forces could possibly have unleashed the torrent of stab wounds that left Luis, Juan and Alexander Fuentes dead in the back of the car in which they'd apparently been living, one child's eyes still open wide?
Authorities allege that their father, Luis Fuentes, inflicted the wounds on the boys and then stabbed himself. They have charged him with murder and say he is the sole suspect in the case. He has not yet entered a plea.
Earlier this month, Fuentes, dressed in a blue suicide prevention gown, sobbed openly as his wheelchair was rolled into a downtown courtroom.
Passing his girlfriend, Josefina Barrales, he issued a plea:
At the boys' wake on Thursday, many of Fuentes' family and friends seemed to be searching desperately for a way to do that.
For the record
1:01 p.m.: An earlier version of this post reported that the wake for the Fuentes boys was Friday. It was Thursday. It also misidentified 3-year-old Andrew Fuentes as the three dead boys' stepbrother. He is their half brother.
Loved ones, including Barrales, with whom he and the boys had shared a home, sobbed over each white casket, kissing the boys on their foreheads and asking for an answer to what happened. Inside the boys lay peacefully, each with a rosary and flowers placed atop their suit-clad bodies.
Three-year-old Andrew, Luis Fuentes' youngest son with Barrales, peered down at his half brothers from his mother's arms, as she blessed each one with a cross.
"Estan mimis," he told his mother, almost as if reassuring her. "They're sleeping."
Paula Trejo, a relative of the boys' mother, was clearly shaken. "We want to blame someone .... We want to know why."
"We have no answers," the deacon told gathered congregants, "but we have plenty of questions."
His words echoed through the same church where the boys' parents had wed.
It was also the church where they and their father had attended a funeral mass seven years ago, after their mother died suddenly of an aneurysm.
Barrales and Fuentes met in the ham-boning department at Farmer John, after he returned from leave after his wife's death.
Fuentes, who loved to dance, would sometimes take Barrales out to the Lido Club in Long Beach for a night of bachata, in which couples hold each other close, sometimes breaking into almost acrobatic moves.
While the two were never married, she wore a promise ring he'd given her and kept the wedding rings he'd bought them stored away in her closet.
Fuentes and Barrales slept in the small home's bedroom with the four young boys in the bunk beds. They dreamed of buying a big house with three or four rooms, Barrales said in Spanish.
"We were a happy family. As a father, as a husband, he was good. I can't speak badly about him. He loves his kids," she said.
Photos of the smiling boys around the house seem to show the kind of loving father many family members and friends say Fuentes had been.
On his sons' birthdays he would sing along with "Las Mananitas," a traditional Mexican birthday song, while snapping photos and videos of the boys.
On Monday afternoons he'd gather with them to watch wrestling. The boys picked their favorites — Luis preferred John Cena and Juan liked Dolph Ziggler. Alex loved them all.
On movie nights, Fuentes would make popcorn and they'd all watch comedies or scary films. When Alex would leave during frightening parts, the older boys would tease him good-naturedly about being "a girl."
"I didn't have a little brother until I met Luis, Juan and Alex, so I never got to experience that," said Victor Galeana, 22, Barrales' son from a previous relationship. "Even though they would get mad at each other, at the end of the day they'd still say they were brothers."
Galeana laughed as he remembered the boys playing out scenes from "The Fast and the Furious" franchise, their favorite movies.
When they weren't reenacting movies scenes or wrestling matches, they'd ask their dad for help on their homework or to kick around a soccer ball outside. When he was too tired to play, Fuentes would peer outside from the sofa, keeping a close eye on the boys.
Today, Barrales can't believe that she missed what she now sees as signs of severe depression. Fuentes had lost his father at a young age, his mother when he was around 18 years old and later his wife. He never went to therapy to deal with the deaths, Barrales said, and she thinks it contributed to his depression.
"I feel bad," Barrales said. "Not to see the signs and know he suffered."
There were other problems in the family as well.
Over the last several years, there had been calls to the county's child abuse hotline alleging abuse in the home, and the Department of Children and Family Services opened and closed cases, officials told The Times. The agency has launched an investigation into whether social workers adequately probed the allegations and whether staff responded appropriately to what they learned.
Barrales acknowledged that a social worker came by the home asking, she said, whether Luis had hit Alex. Barrales said that didn't happen.
But she and Fuentes did have their problems, and in mid-July, Fuentes moved out of the home, Barrales said. He moved his three older sons in with his sister, then left after a month or so.
After that, he would tell Barrales he was staying in a motel, or sometimes sleeping with the boys in his car.
Near the end of August, Barrales said she pleaded with Fuentes to bring the children home. He said he would, and Barrales fixed up their beds, cleaned the house and waited for them to return.
"He didn't bring them."
But they kept talking about reuniting, she said.
The night before the incident, she called Fuentes but he didn't answer.
When he didn't show up for work in the morning, she began to worry. Her voice broke as she recalled the police arriving.
"My dreams of my husband returning, of us being like we were, are gone," Barrales said.
As family members stepped forward to add flowers to the boys' caskets at the burial service on Friday, Barrales clutched Andrew, who laid a hand on each casket.
Under the shade of a nearby tree, Barrales' body shook with sobs as she watched the caskets lowered into the ground, right where their mother lies.
Andrew clasped Barrales' tear-soaked face between his hands and asked her over and over for his brothers.
Every time he asked, she'd point to the boxes in front of them.
"Que es eso?" he asked her, pointing as each box disappeared into the earth. "What is that?"
"Es casa de ellos," she told him, her voice wavering. "It's their home."
Times staff writer Nicole Santa Cruz contributed to this report.