Authorities did not know that Elliot Rodger, whose shooting rampage left six dead and more than a dozen injured in a California college town, owned firearms despite three interactions with the police within the year, the Los Angeles Times reported.
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.
Rodger later wrote in a 137-page manifesto that he sent to his parents, therapist and several others just minutes before launching his shooting spree that he feared the police would foil his plot during that encounter.
"I had the striking and devastating fear that someone had somehow discovered what I was planning to do, and reported me for it," Rodger wrote in the document published in part by The Los Angeles Times.
"If that was the case, the police would have searched my room, found all of my guns and weapons, along with my writings about what I plan to do with them."
The sheriff's office has maintained that the responding officers acted professionally and within state law and the department policies.
(Reporting by Curtis Skinner; Editing by Matt Driskill)