Father of man who murdered six tells of sorrow for victims as students’ parents criticise police handling of case

Elliot Rodger’s father says of killings – we did not see it coming

Peter Rodger spoke to Barbara Walters

The father of a British-born gunman who killed six people in California last month has spoken publicly about the attack for the first time, saying he had believed there was no way that his son "could hurt a flea".

Film-maker Peter Rodger, second unit director on The Hunger Games series of films, spoke of how he continued to be haunted day and night by the actions of his 22-year-old son, Elliot, who stabbed three University of California students and shot three others in the 23 May rampage before killing himself.

"Every night I go to sleep, I wake up and I think of those young men and young women that have died and are injured and were terrorised and my son did that," Rodger said in an interview with Barbara Walters on ABC News's 20/20. "My son caused so much pain and suffering for so many families."

He added: "When you go to sleep normally, you have a nightmare, you wake up and 'oh, everything's OK.'

"Now, I go to sleep, I might have a nice dream and then I wake up and slowly the truth of what happened dawns on me, and, you know, that is that my son was a mass murderer."

He added: "There is no way that I thought this boy could hurt a flea. What I don't get is … we did not see this coming, at all. This is the American horror story, or the world's horror story, is when you have somebody who, on the outside, is one thing and, on the inside, is something different. And you don't see it."

In a video that the gunman uploaded to YouTube before embarking on the killing spree, he identified himself as Elliot Rodger and said that he had spent the first five years of his life in Sussex.

He detailed his so-called "day of retribution", stating that he would take his revenge against humanity.

He also emailed a lengthy written manifesto to his mother, father and therapist that detailed his plans and his contempt for everyone he felt was responsible for his sexual frustration.

It subsequently emerged that police officers who had visited him three weeks before the killings were aware that he had posted disturbing videos online but did not watch them, and they did not know about his final video detailing his "day of retribution" until after the rampage had taken place.

Some family members of the victims have criticised the actions of the police, while others have become vocal advocates for gun control. Last week, the parents of the first three people who were killed said they were frustrated by authorities' handling of the case.

The bodies of Rodger's flatmates, James Hong and David Wang, were found inside their beachside apartment near the University of California's Santa Barbara campus in Isla Vista along with that of a friend who had been visiting them, George Chen.

They had been stabbed to death. It is not clear how the slightly built Rodger was able to overpower them.

In a joint interview, the victims' parents told the Washington Post that they visited the crime scene and saw no blood on the walls or ceiling. Police had removed a 6ft by 5ft piece of carpet in one bedroom and vinyl flooring around the toilet had been cut. The parents expressed unhappiness at the amount of information they had been given, but said the limited amount of material removed from the apartment suggested the killings were confined to a small space.

The three people shot dead were named as Katherine Cooper, 22, and Veronika Weiss, 19, students who were shot outside a sorority house, and Christopher Michael-Martinez, 20, another student who was shot at a delicatessen.

Rodger was found dead with a gunshot wound in his black BMW. He had three 9mm semi-automatic guns and more than 400 rounds of unused ammunition.

The full interview airs on Friday night.