By Holly Yan and Sara Sidner
(CNN) -- As a California university mourns the deaths of six students, grieving parents are bracing to do the unimaginable -- bury their children.
A former stay-at-home dad who worked at home, Bob Weiss had an especially close relationship with his 19-year-old daughter, Veronika. He knew something was amiss Friday night when Veronika, who frequently checked in, didn't call her family.
So he tracked Veronika's cell phone online.
"We got on her iPhone and located it in the middle of the crime scene," Weiss said.
The phone was moving, but no one was answering.
"We actually were looking at her phone while they were moving her body ... probably to take her to the morgue."
Veronika was one of six college students killed by Elliot Rodger, who was bent on killing beautiful women and popular men after years of self-described rejection and jealousy.
The irony, Weiss said, is that Veronika was exactly the kind of person who would want to help Rodger.
"She was kind. She was the person who would reach out to the kids who weren't the popular kids, some of the nerdy kids, some of the kids that were a little bit like this Rodger kid described himself as."
A day of mourning
A cloud of grief has covered the scenic community of Isla Vista since Rodger killed six students from the University of California, Santa Barbara. Thirteen other people were wounded.
The university declared Tuesday to be a formal day of mourning, with a memorial service set for the afternoon.
Counselors are available on campus for anyone needing support, the university said.
'We would die 100 times'
Kelly Wang and Johnny Chen can't understand why their son, George Chen, was stabbed to death by his roommate before the killer went on a shooting rampage. Wang said she would do anything to trade places with her son.
"We would die 100 times,1,000 times, but we don't want our kids to get hurt," Wang told CNN affiliate KABC, weeping.
"This shouldn't happen to any family. This should be the last one in the United States."
A long-planned rampage
The plot may have been years in the making, but the killer gave just minutes' notice before he rained terror across Isla Vista.
Authorities now know Rodger's killing spree began before he even left home.
The 22-year-old former Santa Barbara City College student fatally stabbed three young men in his own apartment -- Chen, 19, Cheng Yuan Hong, 20, and Weihan Wang, 20.
Chen and Hong were the attacker's roommates, and Wang was visiting.
A friend of Rodger's family said Rodger recently had a feud with his roommates, complaining to his landlord that they were too noisy and played lots of video games.
The assailant himself outlined his plan to kill two roommates in a 137-page manifesto.
"I'd even enjoy stabbing them both to death while they slept," Rodger wrote.
The manifesto chronicles his life from birth all the way to his planned "Day of Retribution."
On Friday, minutes before he killed two young women in front of a sorority house and shot a young man at a nearby deli, Rodger e-mailed his writings to two dozen people -- including his parents and at least one of his therapists.
"My orchestration of the Day of Retribution is my attempt to do everything, in my power, to destroy everything I cannot have," Rodger wrote.
"All of those beautiful girls I've desired so much in my life, but can never have because they despise and loathe me, I will destroy."
But it wasn't just beautiful girls he wanted to kill.
"All of those popular people who live hedonistic lives of pleasure, I will destroy, because they never accepted me as one of them," Rodger wrote. "I will kill them all and make them suffer, just as they have made me suffer. It is only fair."
Rodger's mother, Lichin, saw the e-mailed manifesto at 9:17 p.m. Friday. She went to Rodger's YouTube page and saw a disturbing video in which her son talked about "slaughtering" women at a sorority house at the University of California at Santa Barbara, family friend Simon Astaire said.
His mother called her ex-husband and 911, and the parents left from Los Angeles to Santa Barbara, the family friend said. En route, they heard there was a shooting. They later learned out their son was the gunman.
Elliot Rodger was found dead after crashing his black BMW, a gunshot wound to his head.
The assailant had been seeing therapists
Rodger's history of mental health issues was no secret to his family, and the young man was seeing at least two therapists prior to his death.
He had been seeing therapists on and off since he was 8, Astaire said. When he went to high school in Van Nuys, California, he met with a therapist "pretty much every day," Astaire said.
Rodger's family contacted police after discovering social media posts about suicide and killing people, family spokesman and attorney Alan Shifman said.
Six policemen showed up at Rodger's home in Isla Vista on April 30, but they found nothing alarming. So they told Rodger to call his mother and they reassured her that he was OK, Astaire said.
Santa Barbara County Sheriff Bill Brown told reporters that at the time, deputies "determined he did not meet the criteria for an involuntary hold."
Brown said Rodger told deputies he was having troubles with his social life, but that he was not going to hurt himself or anyone else.
Weiss and Katherine Cooper, 22, were members of the Delta Delta Delta sorority at UCSB.
"Katie will be remembered for her generous spirit and warm heart. Veronika will be remembered for her vibrant personality and enthusiasm for life," Delta Delta Delta President Phyllis Durbin Grissom wrote.
The sixth victim killed, Christopher Martinez, was getting a sandwich at a deli when he was shot. The 20-year-old UCSB student was known for his selflessness.
"Chris was just an amazing guy," Jeff Dolphin, Martinez's freshman-year roommate, told the Los Angeles Times.
"If I was going through something, he was always there for me. If I needed something, he was there. If I needed a textbook, if I was locked out of the room because I forgot my key, he would stop playing basketball or doing what he was doing to unlock the door so I didn't have to get charged. He was just a great guy."
Martinez's father, Richard Martinez, lambasted politicians and the National Rifle Association after his son's death. He told CNN's Kyung Lah that nothing has changed since the Sandy Hook Elementary School shootings in 2012, when 20 children and six adults were killed.
"Have we learned nothing? These will continue until somebody does something. Where the hell is the leadership?" Richard Martinez asked.
"He's our only child. And he died on Friday. I'm 61 years old now. I'll never have another child. He's gone."
CNN's Pamela Brown, Todd Leopold, Ashley Fantz, Greg Morrison, Alan Duke and Chelsea J. Carter contributed to this report.
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