In some mass shootings, authorities search for a motive.
But in the case of the suspect in Friday's rampage at Isla Vista near UC Santa Barbara, that appears not to be the case.
The suspect, Elliot Rodger, left videos and a long written statement in which he details his plans and talks about feeling alienated and enraged.
"I'll take great pleasure in slaughtering all of you. You will finally see that I am in truth the superior one, the true alpha male," he says in one video. "Yes, after I have annihilated every single girl in the sorority house I'll take to the streets of Isla Vista and slay every single person I see there."
He also outlined his intentions to kill in a 137-page document that he sent Friday night, shortly before the killings, to someone he knew from an online bodybuilding forum.
Rodger was named by authorities as the suspect in Friday's homicidal rampage that left six people and the gunman dead. He said in a video posted the day the shots were fired: "I will be a god compared to you. You will all be animals. You are animals, and I will slaughter you like animals. I hate all of you. Humanity is a disgusting, wretched, depraved species.… I'll be a god exacting my retribution on all those who deserve it and you do deserve it just for the crime of living a better life than me."
The videos, with titles such as "Life is so unfair because girls don't want me" and "Balcony Vlog, reminiscing about Childhood," show a bitter young man who struggled with adolescence and tried hard to fit in at college. He said he considered himself better than others and should not be rejected by women.
"I'm such a magnificent guy. I'm beautiful, you can't deny that… I'm civilized, intelligent, sophisticated. I have a sense of style, yet you girls don't see it," said Rodger, who law enforcement officials said was a student at Santa Barbara City College.
"Whenever I drive through this college town called Isla Vista, which is just right next to UCSB, I see so many hot beautiful blond girls walking with absolute, stupid obnoxious-looking [men]. And I can't help but think how wrong that is. Those beautiful blond girls should be walking with me, not those brutes."
Filming mostly from the driver's seat of a car, Rodger talks about how rejection from women has formed his world view: "This world is so twisted. It's so cruel. And you girls make it cruel. And you girls have starved me of sex, and enjoyment and pleasure for my entire youth. You've taken eight years away from my life. Eight years I will never get back. Do you know how much misery you've caused me?"
Rodger said in his videos and social media profiles that he is 22, half Asian and born in the U.K. He moved to the U.S. when he was 5 years old and grew up in Calabasas and Woodland Hills.
His "bragging rights" include travels to 10 different countries, walking the red carpet at the "Hunger Games" premiere and attending the red carpet premieres of all the "Star Wars" prequels, according to his Google+ page.
Rodger is the son of Peter Rodger, who was an assistant director on the 2012 film "Hunger Games." Peter Rodger also directed the 2009 documentary "Oh My God," in which various people were asked, "What is God?"
Peter Rodger said through an attorney that he believes his son is the suspect. "I cannot confirm that but we believe it," the attorney, Alan Shifman, told reporters outside the father's home in Woodland Hills.
"The Rodger family offers our deepest compassion and sympathies to the families involved in this terrible tragedy. We are experiencing the most inconceivable pain and our hearts go out to everyone involved," the family said in a statement.
A law enforcement source confirmed that Rodger is believed to have been the shooter.
Some longtime neighbors were surprised that a boy like Elliot Rodger could be capable of Friday's shooting rampage, which Santa Barbara County sheriff's officials have described as what appears to be "premeditated mass murder" and "the work of a mad man."
Neighbor Boris Bakalinsky said he knows the son as well as his father, who has lived in the neighborhood for about 20 years.
"The boy, it's just shocking; we just never expected it," Bakalinsky said.
He said Elliot Rodger was always quiet but very polite, saying hello every time he walked his dog in the neighborhood. He said he thinks he lived part-time with his father, who was separated from his wife.
He said Peter Rodger dedicated his life to his kids and was always with his family. Bakalinsky said he told the young man, "Listen, you have to look at your father, he's a nice father, and follow his example."
Police have been analyzing the videos posted by Elliot, including his most recent video titled "Elliot Rodger's Retribution," in which he threatens violence.
At the end of his sweeping statements in the retribution video, Rodger laughs.