Rodger had legally purchased three firearms leading up to the shooting spree, a fact that authorities could have discovered by searching law enforcement databases, the Times reported on Friday.
"The issue of weapons did not come up," sheriff's spokeswoman Kelly Hoover told the Times. "We had no information that he had weapons or reason to believe he had weapons."
The news comes a day after the sheriff's office revealed new details about a welfare check the police conducted on the night of April 30 on Roger outside his apartment, following a concerned call from a county mental health worker.
That night, just weeks before the killings in Isla Vista, California, a half dozen officers responded to the call and asked Rodger about disturbing videos he had posted online. Police described Rodger as shy, timid and polite, and following the 10 minute meeting, did not consider him a threat to himself or others.
"They did not view the videos or conduct a weapons check on Rodger," a statement from the sheriff's office said.