By Leila Miller, Richard Winton and Alejandra Reyes-Velarde
Los Angeles Times
LOS ANGELES – As Santa Clarita mourned the two students killed in the shooting at Saugus High School, law enforcement authorities tried to uncover a motive for the attack and how the shooter obtained the gun he used.
Throughout the day and into Friday night, residents, students and families came together around a makeshift memorial in Central Park, a short walk from the school.
The teenager who opened fire on his classmates before shooting himself died Friday night at a hospital, authorities said. Officials said his mother was with him.
A key focus of the investigation is how Nathaniel Berhow got the .45-caliber handgun he used to carry out the attack Thursday morning.
The Los Angeles County Sheriff's Department is working with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives to determine whether the gun was made from parts purchased separately and then assembled, law enforcement sources told The Times. Such weapons, so-called ghost guns, do not have serial numbers and can be manufactured from parts ordered through the mail or acquired from underground makers.
Authorities say Berhow carried out the attack on his 16th birthday after being dropped off at school by his mother. They say school surveillance video shows a boy pulling a pistol from his backpack and opening fire in the quad, killing a 15-year-old girl and a 14-year-old boy and wounding three others in an attack that lasted 16 seconds.
At one point during the attack, the weapon jammed and the shooter cleared the firearm before he continued firing. He appeared to know how many shots he had fired and to have left the final round for himself, ending the attack with a gunshot to his head, said Sheriff Alex Villanueva.
He said investigators found several firearms during a search of the teen's home, and some were not registered. Villanueva did not specify what types of guns were recovered.
Berhow's late father is said to have been an avid hunter, but it's unclear if those weapons belonged to him.
Investigators say they think the attack was planned but that no specific students were targeted.
The shooting left the residents of Santa Clarita stunned, and many visited the memorial throughout the day Friday to share their grief.
Dozens of heart-shaped paper cutouts hung on a piece of string that encircled the memorial. On them were notes written by people who knew Gracie Anne Muehlberger, a 15-year-old cheerleader who was one of the students who was killed.
After the shooting, dozens of her friends and members of her cheerleading team met to write the notes and share memories of Gracie.
"Our heart is breaking for her family and we wanted to do something for Gracie and the victims," said Shelly Walker, who had been Muehlberger's coach. "She was super sweet, very respectful, everything you wanted in a student."
Chloe White, 17, who had helped coach the team, said Gracie had a bright personality and enjoyed being on stage.
She was also quick to throw out encouragement to her teammates as they got ready to perform, Chloe said.
"She was always telling people they could do it," Chloe said. "'You got this, guys! You're going to be great!'"
Others who visited the memorial were friends of 14-year-old Dominic Blackwell, the other student killed. Sebastian
Martinez, 12, who played football with Dominic in a youth program, arrived at the park with his father to place a football at the memorial.
The two had been friends and would attend each other's games. Through the boys, Xavier Martinez, Sebastian's father, had also become close friends with Dominic's father and spent most of Thursday with his family.
"He was always smiling and laughing," Sebastian said of Dominic. "It's so unfair."
Some came to the memorial looking for ways that they could help the community.
Dave Lyznick, a member of Saugus High's first graduating class, brought a banner he had made at his signage company to honor the victims. He hung it near the memorial, asking passerby if they wanted to write notes to the victims and their families on it. It steadily filled up.
"Gracie, you were so funny and nice. I loved when we played games and listen(ed) to Taylor Swift," one person wrote. "Dominic, I never personally knew you, but you were always so happy and sweet," wrote another.
The attack had shaken Lyznick deeply. His nephew had been in the quad just a few feet from the gunman when the shooting started and escaped by running from campus. Meanwhile, his niece was inside the school, which was placed on lockdown until authorities were sure the threat was over.
On Friday, Lyznick walked toward the banner to read some of the notes. He stood still, suddenly choked up.
"This is the hardest part now," he said.
The motive for the attack also remains a mystery.
Detectives have conducted 40 interviews and still have six to go in their efforts to piece together what led up to the shooting.
"We are chasing all the leads available," Villanueva said. "At this stage, we don't know the motive."
At the memorial, candles, flowers and teddy bears encircled a pole with an American flag that was lowered to half-staff.
Friends and neighbors of the shooter said they were stunned, and that the teenager had not shown signs of aggression. He ran junior varsity cross-country and helped younger members in his Boy Scout troop.
"He would have fun with the team and was a good kid," 11th-grader Aidan Soto said. "The younger Scouts really looked up to him. He was there when they needed him with anything. I'm bewildered and looking for answers."
Brooke Risley, a 16-year-old junior at Saugus High, had known Berhow since elementary school. Last year, the two were part of a group that worked on a project for their engineering class and became close friends.
"He was very smart and really good at history," she said.
In their AP European history class, she said, he would help her study and would often get the highest test scores in the class. She said Berhow often planned Boy Scout trips during their free time in class.
"He was pretty funny, too," she said. "He had a higher-level type of humor that often I couldn't even get the joke because it was above my head."
When word of the shooting _ and who was responsible _ began to spread, Brooke got the news from a friend. In shock, she began texting a mutual friend.
"Please tell me it's not Nathaniel," she said.
"I heard that too," he responded. "I don't want to believe it."
A senior in their class last year reached out to her Friday, asking whether it was the same Nathaniel who was part of their group project, "because he couldn't believe he would do this," Brooke said.
"Everyone who has heard about him being the shooter has said this wasn't typically him," she said. "All those who know him are really wondering what the motive was."
Public records and a high-ranking law enforcement source indicated signs of trouble at home.
His family life in Santa Clarita was upended by the sudden death of his father, Mark Berhow, in December 2017, acquaintances said. More recently, a source told The Times, the boy was having problems with his girlfriend, who was his emotional anchor.
Mark Berhow had been arrested on suspicion of driving under the influence in 2013 and 2015 and pleaded no contest twice. The second time, he was sentenced to 45 days in jail and five years' probation.
According to jail records, he was also booked in 2015 on suspicion of attempted battery of a spouse. The Los Angeles County district attorney's office declined to file charges in that case, citing insufficient evidence.