Transcript for Elliot Rodger: Inside the Mind of a Killer
california-santa Barbara community is in mourning. The gunman who methodically planned at take, chronicled his descent into a deranged rage. How did this young man who seemed to have everything become a mass murderer? Tonight, we take a close look at the clues and his parents' futile race to try to stop him. ABC's Cecelia Vega is in Santa Barbara. Tomorrow is the day of retribution. Reporter: Is this the latest face of evil in America? You force me to suffer all of my life. And now I will make you all suffer. Reporter: An angry, psychologically twisted young man whose public rantings exploded into sheer terror in a quiet California community. Shots fired! Reporter: Taking six young lives and injuring 13. 22-year-old Elliott rogdger, a virgin vowing revenge in a twisted video he post fried day addressed at his perceived enemies, young women he said rejected him. All those girls I desired so much, they would have all rejected me and looked down upon me as an inferior man. If I ever made a sexual advance toward them. Deep delusions that would turn deadly. I hate all of you. I can't wait to give you exactly what you deserve. Reporter: Tonight the university of California Santa Barbara shut down, classes canceled, flags flying at half staff, a community in mourning. Thousand coming together for an emotional memorial service. ? ? Let us cherish the moments that we have shared with them. And be grateful to have had them in our lives as friends, as family, and as loved ones. And now new details are emerging about Rodger's life, his parents, divorced his father, peter Rodger, respected director who worked on "The hunger games." But their son Elliot lived his life as an angry outsider the of a family spokesman telling ABC news, Rodger had been in therapy since 9 years old, this painfully shy young man creating on video what he couldn't in life. I have waited a long time for this. The killer's attempt to re-create his persona in a sympathetic way, in a way where he can get understanding, relevance, meaning, where his life has no meaning at all. This was a plan years in the making. Executed methodically. The apparent revenge, fantasy set in motion Friday night at 9:17 P.M., Rodgers therapist calls his mother, alerting her to an e-mail from her son, a manifesto called my twisted world. 137 pages pouring from this tortured mind. Idyllic childhood memories, painful teenage years, and finally, an elaborate plot to kill. He is so invested in carrying out the mass killing, that he will sit down and write and edit and reedit something that amounts to 140 pages. Make a variety of different videos, and mobilize to a degree that this becomes a project, an ambition, a career path. His mother, alarmed, checked her son's youtube channel. Immediately she called her ex-husband and they raced to Santa Barbara saying they called police along the way. But it ties late. The first three victims already dead. Rodgers two roommates, along with their friend, all stabbed to death in this apartment building. A death too terrible for George Chen's parents to even contemplate. I just don't know why this happened to our son. I just, it's crazy. This 'just doesn't make any sense. At 9:27, the first reports of a mass shooting under way. Shots fire. Shots fired. As soon as we heard the noise. It was so close and terrifying. Rodger's next target, a sorority, he says to take revenge against all the girls who have rejected him. After I have annihilated every girltee -- sat roar tee house I will take to the streets of Isla vista, I will slay every person I see there. This young man seemed to have a lack of skills and ability to interact with any body, let alone the opposite sex. He banged on the door of the sorority, when nobody let him in he shot three women around the corner, killing two, Katherine cooper and Veronica Weiss. But Rodger's rampage wasn't over. 9:30 P.M., opens fire at this deli filled with students. Surveillance shows people diving for cover. I thought that was my last moment. His final victim, Christopher Michaels Martinez. I gave him cpr for ten minutes before paramedics showed up. Our son was the most important thing in the world to all of us. He was our only child. So much a part of our lives. It is hard to imagine how things are going to be look now that he is gone. At the end, Rodger driving in the black BMW, plowed down bikers and indiscriminately shot pedestrians. Some guy, ran in the house, bleeding, said he got run over with the car. This man was skateboarding when Rodgers ran into him. Sending him flying into the air. Both legs are broken. His left leg was come letly shattered. By 9:33 it was over. Rodger and police in a gunfight. The killer drives away. Crashes his bmwa. Parentally turning the gun on himself. Police say they found 400 round of ammunition in Rodgers' car and he carried out his shootings with legally purchased semiautomatic handguns. He was under psychiatric care. His parents saying they did everything they could to help a shy, reclusive son, even reporting his disturbing videos to police last month. Police went to his home, but say they found no cause to search it or order a mental evaluation. Because of narrowness of the law, danger to self, others, grave disability, those officers acted in accordance with the law. En his manifesto, Rodger wrote if the police searched my room. Found all my guns and weapons I would have been thrown in jail, denied of the chance to exact reren V revenge on my enemies. Thankfully that wasn't the case. But it was so close. We send the authorities, not mental health professionals to check on this young man. And it takes a very trained eye and, a lot of skill, to decide whether or not this person is a risk to hurting themselves or hurting others. His anger, sexual rejection, morphing to misogynistic diatribes. Girls gave their affection and sex and love to other men but never to me. Now, a worldwide outpouring. More than a million tweets. Decrying a culture that turns women into sex objects, #yesallwomen, now fighting back. Because every woman I know has experienced some form of sexual harassment, abuse or assault. Myself included. And on sccampus, remembering those lost, sharing the pain and searching for answers. If you agree the people in Washington should hear that not one more person should have to die because of this ridiculous situation, then when I raise my hand, I want you to shout so loud they're going to hear you. Yes! Not one more! Not one more! For "Nightline," Cecelia Vega, in Santa Barbara, California. But often that search for answers can be so difficult. Thanks, Cecelia. Coming up.
This transcript has been automatically generated and may not be 100% accurate.