The university and nearby Isla Vista, Calif., are mourning the victims of a 22-year-old student who stabbed three people in his apartment and fatally shot three others on the streets of the community. The shooter was found dead in his car. The mass killing has rekindled a long-simmering debate about gun control and mental health care in the country.

The university and nearby Isla Vista, Calif., are mourning the victims of a 22-year-old student who stabbed three people in his apartment and fatally shot three others on the streets of the community.

The university and nearby Isla Vista, Calif., are mourning the victims of a 22-year-old student who stabbed three people in his apartment and fatally shot three others on the streets of the community.

With the toughest gun-control regulations in the country, California has a unique, centralized database of gun purchases that law enforcement can easily search. It offers precious intelligence about a suspect or other people officers may encounter when responding to a call.

But this rare advantage wasn’t enough to help authorities head off the May 23 rampage in Santa Barbara that claimed six victims.

Before a half-dozen sheriff’s deputies knocked on Elliot Rodger’s door last month in response to concerns raised by his mother about his well-being, they could have checked the database and discovered he had bought three 9mm semiautomatic handguns. Several law enforcement officials and legal experts on gun policy said this might have given deputies greater insight into Rodger’s intentions and his capability for doing harm.

The deputies did not check the database. They left his apartment after finding him to be “shy, timid, polite and well-spoken,” in the words of Santa Barbara County Sheriff Bill Brown. The deputies saw no evidence that Rodger was an immediate threat to others or to himself.

“I cringed when I learned they didn’t run for guns,” said Emeryville Police Chief Ken James, who is chairman of the California Police Chiefs Association’s firearms committee.

Students at the University of California at Santa Barbara mourn the loss of their classmates four days after six students were killed in a stabbing and shooting rampage across the community. (Reuters)

James said law enforcement officials are not required to check the Dealer’s Record of Sale (DROS) database before going to the home of someone who is potentially suicidal. But after the killings in Santa Barbara, he said he expects it will become more common.

“Each agency has their own policy on this. Most leave that to the discretion of the officers who are going on the call,” James said. “I don’t know if it will be necessary to require it in the future. I believe officers will begin to do this on their own because of what happened. They will be more aware of this and act on it.”

Traditionally, law enforcement officers infrequently consult the DROS database when conducting what is known as a “wellness check” on people who may be suicidal but are not threatening violence.

After the rampage, the Santa Barbara County Sheriff’s Department confiscated a Glock 34 and two Sig Sauer P226 handguns from Rodger’s black BMW. They also found 41 loaded 10-round magazines in his car and recovered five empty magazines.

In his 137-page manifesto, which he posted online just before the shootings, Rodger wrote about the April visit by deputies. “The police interrogated me outside for a few minutes, asking me if I had suicidal thoughts. . . . If they had demanded to search my room . . . That would have ended everything. For a few horrible seconds I thought it was all over.”

Instead, it was only after the killings that the sheriff’s department concluded that Rodger, 22, was a “mad man.”

“Their assessment could have changed if they knew about the gun purchases and asked him about them,” said Daniel W. Webster, director of the Johns Hopkins Center for Gun Policy and Research. “They could have asked to see the guns. They could have let him know they knew he had them.”

The sheriff’s department did not respond to requests for additional comments regarding the decision to forgo checking the DROS database before going to Rodger’s apartment in Isla Vista. In a statement Thursday, the department said, based on the information it had at the time, Rodger did not seem to be an immediate threat to himself or others, so no weapons check was done.

The database includes the names of gun dealers who sold weapons to Rodger, and if the deputies had called the dealers, the scope of his ammunition purchases might have emerged.

Garen J. Wintemute, director of the University of California at Davis’s Violence Prevention Research Program, said knowledge of the guns could have been helpful, but knowledge of large ammunition purchases would have triggered a more urgent need to intervene.

“If they found out he bought 40 magazines, that would have been the end of it,” said Wintemute, who is also an emergency room doctor and professor of emergency medicine. “I don’t think anyone could talk their way out of 40 magazines. Three handguns could be aggressive collecting; 40 magazines is stockpiling. You are preparing for some kind of event. With the family saying he was possibly suicidal, it wouldn’t have been too hard to connect the dots.”

Police typically check the DROS database when they receive calls or other information about persons who may be threatening to do immediate harm to themselves or others, particularly in instances of domestic violence, law enforcement officials said. It’s far less common to check the database when responding to calls about people who may be suicidal, they said.

Capitola Police Chief Rudy Escalante said, for instance, that it would be “virtually impossible” to consult the database for every person who is acting strangely.

“You wouldn’t get everything done,” he said. “You have to have a threat that is happening now or some real information that there is an immediate threat.”

James said that even if deputies had known about the guns and ammunition, it might not have changed the tragic outcome. But he and other law enforcement officials said two other scenarios might have unfolded.

First, deputies could have confronted Rodger with the details of his purchases and asked to see the firearms, requesting that he surrender them. Rodger might have complied if pressed.

Second, the deputies could have returned to Rodger’s family with the information about the gun purchases and asked for more details about his situation. This could have helped the deputies secure a search warrant and to make the case that he was a danger to himself and possibly others, giving them the authority to seize the weapons.

The DROS database is unique to California. Seven other states have some type of requirement for retailers to report details of gun sales to a state agency, but not all of them have an easily searchable database like California’s, according to Webster.

For decades, the California system has required firearms retailers to report handgun purchases, including the buyer’s name and address and details about the handgun. In January, California began to require that retailers report the same information for long guns, which include rifles and shotguns. The sale of assault rifles is banned in the state.

Technically, the database is not a registry, but rather a record of a firearm “transfers.” It records nearly all gun sales, because California law prohibits the sale of guns between private parties.

Santa Barbara sheriff’s deputies and a University of Santa Barbara police officer were dispatched to Rodger’s apartment after his mother saw disturbing videos he had posted on YouTube, according to the sheriff’s department. Worried about his well-being, she called his therapist, who in turn contacted a mental health service. The service referred the matter to law enforcement, conveying his mother’s concern that Rodger might be suicidal and information about the videos.

The sheriff’s department Thursday updated its timeline of events, disclosing that deputies had been informed of disturbing videos Roger had posted on YouTube, but did not view them before or after leaving his apartment. They did ask him about the videos.

“When questioned by the deputies about reported disturbing videos he had posted on-line, Rodger told them he was having trouble fitting in socially in Isla Vista and the videos were merely a way of expressing himself,” the sheriff’s department said on its Facebook page. “Based upon the information available to them at the time, Sheriff’s deputies concluded that Rodger was not an immediate threat to himself or others, and that they did not have cause to place him on an involuntary mental health hold, or to enter or search his residence. Therefore, they did not view the videos or conduct a weapons check on Rodger.”

Rodger removed the videos after the visit by sheriff’s deputies, but in May uploaded them again on YouTube, where they remain. In them, he complains bitterly about his loneliness, isolation, and lack of any attention from women, but he does not threaten violence against anyone. His mother believed they showed he was suicidal.

Escalante, the Capitola police chief, said that viewing the videos before going to the apartment might have given deputies more leverage to secure a search warrant.

As for checking the DROS database, it is easy, taking a matter of minutes if law enforcement officials have a person’s legal name and date of birth, as they did with Rodger.

The database is housed inside the California Law Enforcement Telecommunications System, which is essentially a warehouse of databases. CLETS also contains separate gun licensing information, which is recorded at the time of the gun purchase. But this database does not provide officers with any information beyond that contained in DROS and often has fewer details.

Gun rights groups said the Santa Barbara episode shows that existing laws are not used by law enforcement and that more gun-control regulations are not needed.

“The state knew he had firearms. What is the point of registration if they are not going to make use of that information with someone who is clearly mentally unstable?” said Brandon Combs, president of the California Association of Federal Firearms Licensees, which lobbies on behalf of gun dealers and collectors on gun policy. “I think the shooting in Santa Barbara is about the failure to enforce existing law.”

After the shootings, state Sen. Kevin de León (D-San Diego), renewed calls for a statewide database that would track detailed information about ammunition purchases.

The state Senate passed Senate Bill 53 in August, which would mandate the ammunition sales reporting system. It is now in the state Assembly and is expected to be taken up in next month in the public safety committee.

“My focus is ammunition. This is what fuels the violence,” de León said. “Anyone can walk into any gun store and buy all the ammunition they want — no questions asked. We do not know who sells or who buys ammunition.”

The bill is modeled after local ordinances in more than a dozen cities and counties in California. Local officials have reported using this information to solve crimes and to confiscate ammunition purchased by convicted felons, who are not allowed to own firearms in the state. (None of the cities or counties where Rodger made his gun purchases has such an ordinance. It is unclear where all his ammunition purchases were made.)

Sixty cities, domestic violence groups, religious organizations, local law enforcement departments and gun control groups have signed on as supporters of the bill. Eight gun rights groups are officially opposed to it.

Combs’s group is among those opposed to the bill.

“As the bill is written, you can’t dispose of ammunition in any current, lawful way. You can’t even sell it back to a vendor,” Combs said. “Even if you buy a case and you use it all, the government doesn’t know that, because it doesn’t have provision for that. So it forces you to stockpile ammunition.”

Crites reported from Washington.