Two machetes, a hammer and a knife were among the items removed from the ground floor corner apartment they shared behind a row of palm trees at the Capri complex in Isla Vista.
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A day before the massacre, Rodger had compiled a 141-page manifesto, in which described how he intended to use the hammer to knock out his room-mates and then slit their throats "to secure the entire apartment for myself as my personal torture and killing chamber". He had saved more than $5,000 in pocket money sent to him by his parents and grandmothers, which he used to buy at least three semi-automatic handguns and more than 400 rounds of ammunition. After doing so he wrote: "Who's the alpha male now?"
Watch: Shooting rampage - raw footage
A neighbour at the Capri said Rodger had been taken to hospital with an injured ankle after being pushed off a ledge in a fight in July. He said: "He was so emotional. I've never seen anybody that mad. He said, 'I'm going to kill all of them. I'm going to kill myself'. I don't know if that's what set the plan in motion."
He described once taking Rodger to a party but he was "like a ghost" and "just stared at people".
According to his manifesto, Rodger developed an irrational hatred of several blonde women. They included the first girl on whom he had a "crush" at the age of 14, who grew up to be a model, and the first girl with whom he was friends as a child who also became a "popular" person. They have declined to comment.
A vigil to honour the victims of the mass shooting in Isla Vista. Photo / AP
Minutes before opening fire in central Isla Vista, Rodger emailed his manifesto to 30 people including his parents, therapists and former teachers. It is believed he may have already killed the three men in his house by then - Mr Hong and fellow overseas students George Chen, 19, and Weihan Wang, 20.
One of the therapists immediately telephoned Rodger's mother Chin Rodger.
The time was 9.17pm on Friday (local time), about 13 minutes before the massacre began.
She telephoned her husband, Peter Rodger, assistant director of the Hunger Games films, from whom she is divorced. They both began racing from Los Angeles to Isla Vista in separate cars. Both heard details of the massacre on their car radios.
By then, Rodger had shot Katie Cooper, 20 and Veronika Weiss, 19, outside a sorority house and Christopher Martinez, 20, in a nearby deli.
All were fellow students, who he is not believed to have known, at the University of California Santa Barbara.
He then drove around Isla Vista in his black BMW firing wildly out the window before shooting himself dead.
A makeshift memorial where part of the mass shooting took place. Photo / AP
Simon Astaire, a family friend, said Rodger had been seeing therapists since the age of eight, including virtually "every day" while at high school. He said: "What more could they [his parents] have done? They are going through indescribable grief dealing with the loss of their son. His parents were conscious and concerned about their son's health. They thought he was in good hands."
Mr Astaire said Rodger, who was believed to have Asperger's but had not been diagnosed, was "reserved to a daunting degree" and "fundamentally withdrawn", but seemed to have "no affinity to guns whatsoever".
Other friends of Peter Rodger said he was "heartbroken" and "did everything he could", including engaging top specialists, but his son turned his back on therapy as an adult and refused to take medication.
Watch: Killer's YouTube video
Police visited him at the Capri on April 30 after being alerted by his mother to disturbing videos on YouTube. But they did not search the apartment. Mr Astaire said: "That was a pivotal moment, in hindsight. It was pivotal because the apartment was full of guns."
The Santa Barbara Sheriff's Department has begun an internal investigation. But Sheriff Bill Brown said Rodger had not been institutionalised for mental health issues and had no criminal record and they had not had the power to take further action.
He said: "The sheriff's deputies found him to be shy, polite and well spoken. He said it was a misunderstanding and had a convincing story." In his manifesto Rodger said he felt a "wave of relief" as they left.
Jenni Rodger, an aunt of Rodger's living in France, said: "He was always a disturbed child. I don't know how he was allowed to get a gun. Something has to be done about gun laws in America. Pete is absolutely broken. I can't see how he'll ever recover."
