The angst leading up to the evening of horror was years in the making.
Elliot Rodger was frustrated by troubles such as his height, his parents' divorce and his lack of success with women -- and wrote 140 pages detailing as much.
After chronicling his years of perceived misfortune, he picked Friday as the day to launch a killing rampage.
It started at his own home in Isla Vista, near the scenic beaches of Southern California. Rodger, 22, stabbed three men repeatedly at his home.
All three of the men died.
Next stop in his rampage: the Alpha Phi sorority house near the University of California, Santa Barbara.
Rodger hinted at the carnage he'd inflict at the sorority house in a YouTube video posted the day before, called "Retribution."
"On the day of retribution I'm going to enter the hottest sorority house of UCSB," he said in the video. "I'll take great pleasure in slaughtering all of you."
On Friday night, sorority members heard loud knocking on the front door for several minutes -- but nobody answered.
Minutes later, Rodger sprayed bullets at the house from across the street, Santa Barbara County Sheriff Bill Brown said.
Witness Kyle Sullivan saw three young women lying on the front lawn.
"There was a young girl, laying right here. And she was -- I could tell immediately she was gone," said Sullivan, 19. "I saw a gunshot wound to her abdomen, also one to her side and one through her head."
She wasn't alone.
"There was a girl right here and she was really struggling. You could tell she was barely able to move her eyes and just moving her arms slightly," Sullivan said. "And there was another girl right here. You could tell she was lying down crouched. She was still conscious, talking."
By the end of the night, two of the three young women died -- Katherine Cooper, 22, and Veronika Weiss, 19. Both were students at UC Santa Barbara.
Alpha Phi posted on its Facebook page Saturday that "all our members are safe."
Rodger then zoomed around town in a black BMW, picking a delicatessen as his next stop. He got out, stepped inside the deli and shot and killed Christopher Martinez, aanother UC Santa Barbara student.
Exactly why, no one knows for sure.
But Rodger's spree was far from over.
He kept dashing around town, allegedly driving down the wrong side of the road so he could fire out the driver's side window near the sidewalk. He shot at two people on the sidewalk, pulled a handgun on a female and fired some more, Brown said.
He encountered a sheriff's deputy who was on foot and exchanged gunfire.
Witness Ian Papa said he was inches away on the street when the gunman's car sped up and struck two bicyclists.
"It happened so fast," he said. "I had no time to react. I jumped on the sidewalk and I see a man on a BMW, his body inside the windshield and glass broken everywhere. ... I almost wanted to break into tears."
The nightmare finally ended after Rodger slammed into a parked vehicle and apparently shot himself in the head, police said.
By the time the melee was over, six victims were dead, 13 were injured, and a quiet beachfront community was left to wonder how this could happen -- and whether anyone could have prevented it.
'Day of Retribution'
In the nearly seven-minute video posted Thursday, Rodger rants about women who ignored or rejected him over the past eight years, "since I hit puberty."
"Tomorrow is the day of retribution, the day in which I will have my revenge," he says in the video. "You girls have never been attracted to me. I don't know why you girls aren't attracted to me, but I will punish you all for it." He specifically criticized sorority members.
Rodger appears to have further chronicled his rage in a 140-page account of his life that begins with his birth and ends with "the Day of Retribution." The manifesto, titled "My Twisted World," was obtained by CNN affiliate KEYT.
"It was apparent he was very mentally disturbed," Brown said.
So disturbed that a relative asked law enforcement officers to check on his welfare April 30, Brown said.
Rodger's family contacted police after discovering social media posts about suicide and killing people, family spokesman and attorney Alan Shifman told reporters Saturday.
Brown said Rodger told them he was not going to hurt anyone or himself. He told deputies he was having troubles with his social life.
"He was articulate. He was polite. He was timid," Brown said.
There was nothing in his behavior to suggest he was violent, and the deputies "determined he did not meet the criteria for an involuntary hold," he said.
It appears that Rodger was planning the killing spree "for at least a year," Brown told CNN on Sunday morning.
It's unclear what Rodger might have done had he not wrecked his car. Inside the wrecked BMW, Brown said, police found three handguns -- all legally purchased -- and more than 400 rounds of unused ammunition. Brown said the guns were purchased the firearms over the past year in three different cities.
Martinez's father, Richard, said some politicians and the National Rifle Association are also to blame for his son's death.
"Chris died because of craven, irresponsible politicians and the NRA," he said. "They talk about gun rights -- what about Chris' right to live? When will this insanity stop?"
Rodger suffered from an undisclosed mental health issue, and was under the care of a variety of health care professionals, Brown said.
But there was no indication he had been committed to a mental health facility.
Rodger passed the background check needed to buy the firearm used in the shooting, a law enforcement official briefed on the investigation told CNN. The official said nothing had been found in the gun trace to indicate Rodger shouldn't have qualified to buy a gun.
In the manuscript of his life's story, he often mentioned feeling slighted or inferior, such as when he was denied entry on an amusement park ride at age 6 while other boys his age got to go on.
"Being denied entry on a simple amusement park ride due to my height may seem like only a small injustice, but it was big for me at time," Rodger wrote. "Little did I know, this injustice was very small indeed compared to all the things I'll be denied in the future because of my height."
He described his parents' divorce as a devastating, "life-changing event," but said he gained more respect for his father after he quickly acquired a girlfriend.
"Males who can easily find female mates garner more respect from their fellow men, even children," Rodger wrote. "How ironic is it that my father, one of those men who could easily find a girlfriend, has a son who would struggle all his life to find a girlfriend."
But the overarching theme of the manifesto focuses on his frustrations with women.
"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. All of those popular people who live hedonistic lives of pleasure, I will destroy, because they never accepted me as one of them. I will kill them all and make them suffer, just as they have made me suffer. It is only fair."