Elliot Rodger
A frame grab from a video that was posted on You Tube by an individual who identified himself as Elliot Rodger is shown in this May 24, 2014 photoReuters

Elliot Rodger, the California gunman who stabbed to death three people in his apartment before going on a shooting spree in the university community of Isla Vista, California, on May 23, was said to be mentally deranged and had planned his attacked about a year before he acted on it, reports indicate.

Rodger, a 22-year-old, committed suicide before stabbing and shooting six people. He had sent out a detailed manifesto of his plans before embarking on the murderous rampage. 

Here are the five things to know about the shooter.

Elliot Rodger is the son of Hollywood director Peter Rodger

Peter Rodger was the assistant director of "The Hunger Games." He was also the director of the 2009 documentary "Oh My God."

He planned the attack almost a year back

Rodger mailed to a select few a 141-page document explaining why he wanted to kill others. In it, he also explained that the plan has been on for almost a year and at one point he feared his intentions would be exposed when a family member called police officials to check on Rodger.

Rodger wrote that he was relieved when deputies left his apartment without checking the premises as they would have found his writings and video if they had done so.

He planned to kill sorority girls

"He targeted sorority girls, and he banged on the door of Alpha Phi and no one answered," an eyewitness told HollywoodLife.com. "His plan was to go in there. But they didn't open so he shot people outside."

Before embarking on the shooting spree, Rodger had uploaded on YouTube a video titled "Elliot Rodger's Retribution," where he said he would kill good-looking people.

Rodger had apparently become so frustrated about his virgin status that he began to despise others who were getting some action. In the chilling YouTube video, which has since been taken down, Rodger explained that he will seek revenge on all the girls who had rejected him in the past.

"If I can't have you, girls, I will destroy you. You denied me a happy life. In turn, I will deny you life. It's only fair," he said in the video.

"College is the time when everyone experiences those things such as sex and fun and pleasure," Rodger said in his video. "But in those years I've had to rot in loneliness. It's not fair. 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."

Click here for the video.

Rodger was mentally ill

Soon after Rodger was identified as the killer, Alan Schifman, the Rodger family lawyer, revealed that Rodger was being treated by multiple therapists. And, Santa Barbara County Sheriff Bill Brown said that it was "very, very apparent he was severely mentally disturbed," Chicago Tribune reported.

Cathleen Bloeser, 58, whose son was a childhood friend of the shooter, told the Chicago Tribune that Rodger was bullied as a child and was known to have Asperger's syndrome.

Reportedly, he once spoke to Bloeser's son about wanting to rape a woman. She also added that Rodger was under psychiatric care for the past one year, but he was not taking his medication.

Rodger was active in an anti-women forum

Rodger was allegedly part of a anti-women group, PuaHate.com, a website that has men who are unable to pick up girls, as its members, Daily Mail reported.

"If you could release a virus that would kill every single man on Earth, except for yourself because you would have the antidote, would you do it? You will be the only man left, with all the females. You would be able to have your pick of any beautiful woman you want, as well as having dealt vengeance on the men who took them from you. Imagine how satisfying that would be," Rodger reportedly wrote on the website last year.