A lawyer of film director Peter Rodger says the family called police several weeks ago after being alarmed by YouTube videos posted by his son "regarding suicide and the killing of people".
The attorney said police had conducted an investigation and interviewed the man. Police said the man appeared to have trouble making friends but did not find a history of guns.
Police have not formally named the suspect, who died following the attack.
More top news
An astronaut has set off for NASA's first year-long mission to the International Space Station - leaving his identical twin back on Earth.
Taking money from the rich to give to the poor is a debate as old as Nottingham's mythic son, so why are people still so divided on welfare?
An unsettled weekend of weather is in store as conditions turn wet and windy from the west tonight.