Rodger's family has disclosed their son was under the care of therapists.
"Once again, we are grieving over deaths and devastation caused by a young man who was sending up red flags for danger that failed to produce intervention in time to avert tragedy," Fuller said in a statement.
"In this case, the red flags were so big the killer's parents had called police ... and yet the system failed," she said.
Rodger, writing in a manifesto, said he was relieved his apartment wasn't searched because deputies would have uncovered the cache of weapons he used in the beach town rampage Friday in which he killed six people and then, authorities say, himself.
He posted at least 22 YouTube videos. He wrote in his manifesto that he uploaded most of his videos in the week leading up to April 26, when he originally planned to carry out his attacks. He postponed his plan after catching a cold.