Chin Rodger got the call from her son Elliot's therapist at 9.17pm on Friday - 13 minutes before authorities say he opened fire outside a sorority house.
"Have you gotten Elliot's email?" he said. "I think you should see it."
Ms Rodger opened the email, saw the first few lines of a 137-page screed Elliot wrote and instantly knew something was terribly wrong, said Simon Astaire, a family friend, who is a Hollywood talent agent and media adviser. He provided this account on behalf of the family in an interview with the Los Angeles Times.
Ms Rodger immediately checked Elliot's YouTube channel, where he had posted bizarre videos about how alienated he felt, particularly from women. On top of the video queue was one called Elliot Rodger's Retribution.
"Well, this is my last video, it all has come to this," he started, speaking coldly and confidently, not his usual timid tone.
"Tomorrow is the day of retribution, the day in which I will have my revenge against humanity, against all of you."
The 22-year-old student at Santa Barbara City College complained about how girls were not attracted to him, throwing themselves at "obnoxious men, instead of me, the supreme gentleman".
After just over two minutes, he said: "On the day of retribution I am going to enter the hottest sorority house of UCSB and I will slaughter every single spoiled, stuck-up blonde slut I see inside there."
Ms Rodger frantically called her ex-husband Peter, a Hollywood director and photographer, who was dining with his wife and two friends.
They decided to race to Isla Vista, the college community outside Santa Barbara where Elliot lived.
Mr Astaire said Ms Rodger called either 911 or the sheriff directly, and arranged to meet authorities when they arrived. As they drove up the 101 Freeway from Los Angeles, they heard news of a shooting in Isla Vista on the radio. Elliot is accused of killing six people before taking his own life.
Ms Rodger called Elliot's therapist, who told her the shooting was unrelated. He said Elliot had promised retribution the following day, and his nature was to stick to such details.
This was the second time in recent months that Elliot's mother tried to intervene in his life. In April, she saw bizarre videos he had posted on YouTube, though not the menacing ones he posted shortly before the rampage, Mr Astaire said.
She called his therapist, saying she was worried about his well-being. He called a mental health service and they referred it to police, Mr Astaire said. A half dozen officers showed up at his door on April 30.
"I heard a knock on my apartment door," Elliot wrote in the diatribe he would later send out. "I opened it to see seven police officers asking for me."
He wrote that "the biggest fear I had ever felt in my life overcame me".
He had three semi-automatic weapons in his bedroom and had written up plans for his assault.
"I tactfully told them that it was all a misunderstanding, and they finally left. If they had demanded to search my room ... that would have ended everything," he wrote.
"For a few horrible seconds I thought it was all over. When they left, the biggest wave of relief swept over me."
Mr Astaire said the family couldn't judge the officers' actions in hindsight. Obviously, given what happened, they wished the police had searched the room.
But Mr Astaire said the family never suspected Elliot would have guns.
"He had no affinity, it seemed, to guns whatsoever," he said.
Mr Astaire said Elliot played the video game World of Warcraft, but wasn't "obsessed with guns or war games".
Mr Astaire said Elliot had not been diagnosed with Asperger's but the family suspected he was on the spectrum, and had been in therapy for years.
He said he knew of no other mental illnesses, but Elliot truly had no friends, as he said in his videos and writings.
Mr Astaire said Elliot was incredibly shy, spoke haltingly and rarely looked people in the eye.
"He was fundamentally withdrawn," he said. "The guy on the video was much more confident. That is a guy I never met."
- Los Angeles Times