By law, Roy Perez should not have had a gun three years ago when he shot his mother 16 times in their home in Baldwin Park, Calif., killing her, and then went next door and killed a woman and her 4-year-old daughter.
Mr. Perez, who pleaded guilty to three counts of murder and was sentenced last year to life in prison, had a history of mental health issues. As a result, even though in 2004 he legally bought the 9-millimeter Glock 26 handgun he used, at the time of the shootings his name was in a statewide law enforcement database as someone whose gun should be taken away, according to the authorities.
The case highlights a serious vulnerability when it comes to keeping guns out of the hands of the mentally unstable and others, not just in California but across the country.
In the wake of the Tucson shootings, much attention has been paid to various categories of people who are legally barred from buying handguns — those who have been “adjudicated as a mental defective,” have felony convictions, have committed domestic violence misdemeanors and so on. The focus has almost entirely been on gaps in the federal background check system that is supposed to deny guns to these prohibited buyers.
There is, however, another major blind spot in the system.
Tens of thousands of gun owners, like Mr. Perez, bought their weapons legally but under the law should no longer have them because of subsequent mental health or criminal issues. In Mr. Perez’s case, he had been held involuntarily by the authorities several times for psychiatric evaluation, which in California bars a person from possessing a gun for five years.
Policing these prohibitions is difficult, however, in most states. The authorities usually have to stumble upon the weapon in, say, a traffic stop or some other encounter, and run the person’s name through various record checks.
California is unique in the country, gun control advocates say, because of its computerized database, the Armed Prohibited Persons System. It was created, in part, to enable law enforcement officials to handle the issue pre-emptively, actively identifying people who legally bought handguns, or registered assault weapons, but are now prohibited from having them.
The list had 18,374 names on it as of the beginning of this month — 15 to 20 are added a day — swamping law enforcement’s ability to keep up. Some police departments admitted that they had not even tried.
The people currently in the database are believed to be in possession of 34,101 handguns and 1,590 assault weapons, said Steven Lindley, acting chief of the firearms bureau in the state’s Department of Justice. He estimated that 30 percent to 35 percent of the people on the list were there for mental health reasons.
Despite the enforcement challenges, the state’s database offers a window into how extensive the problem is likely to be across the country. Concrete figures on the scope of the issue are difficult to come by because no other state matches gun purchase records after the fact with criminal and mental health files as California does.
“There are 18,000 people on California’s list,” said Dr. Garen J. Wintemute, director of the Violence Prevention Research Program at the University of California, Davis, who helped law enforcement officials set up the system and is working on a proposal to evaluate its effectiveness. “So we can roughly extrapolate there are 180,000 such people across the country, just based on differences across populations.”
By way of context, Dr. Wintemute said that in 2009 only about 150,000 people were prevented from buying a gun because they failed background checks, out of about 10.8 million who applied.
Only a handful of states, however, even have the ability to keep track of handgun purchases the way California does, by either requiring a license or permit to own one or simply keeping records of such purchases. Even fewer require a license or permit for other types of firearms.
California’s system came about through a 2002 law that was even supported by the National Rifle Association, in part because it was billed as a way to protect members of law enforcement. It finally got under way in earnest in 2007. But though gun control advocates consider it a model, it still has serious gaps.
The system relies on records kept by the state on handgun purchases, but the state does not retain records of most rifle and shotgun purchases. There were 255,504 long guns sold in California in 2009 alone, compared with 228,368 handguns, according to state figures.
Perhaps most important, the burden for confiscating weapons falls largely on local jurisdictions, most of which are too short on resources to do much. Some may also have been only dimly aware of how the list works.
Police departments and sheriff’s offices that request access to the list of barred owners can log in to a secure account on the state Justice Department’s Web site and get monthly updates of who is on the list in their jurisdictions, with newly added names flagged. The Justice Department also trained more than 1,300 law enforcement officers around the state on the system in 2007 and plans another round this year.
It appears, however, that in the case of Mr. Perez, the Baldwin Park police were not checking the list at all in 2008, when the shootings occurred, in part because of confusion over how to access the database.
“Nobody knew where the e-mail was or where it was going,” said Lt. Joseph Cowan, head of detectives for the Baldwin Park Police Department.
Even today, Lieutenant Cowan acknowledged, his department rarely looks at the list, and he initially said he had no idea how many people in the city were on it. (He later checked and discovered there were about 35 people in his 6.6-square-mile district.)
“We try to get on,” he said. “But with staffing levels what they are, it’s difficult.”
A total of 37 police departments and three county sheriff’s offices in the state have not even signed up to get access to the database, despite receiving yearly notices, said Mr. Lindley, of the firearms bureau.
After being contacted by a reporter, two police departments — in East Palo Alto and Redwood City — said they had not subscribed to the database but would now do so, professing some confusion about the way the system functioned.
Capt. Chris Cesena of the Redwood City Police Department said he had been under the impression that state officials would call if anyone in Redwood City showed up on the list. Only after the department signed up recently did it discover there were 29 people in the city on the list, including seven for mental health reasons.
Detective Vic Brown, a supervisor in the Los Angeles Police Department gun unit, coordinates operations to disarm the roughly 2,700 city residents on the list.
“We just don’t have enough manpower to pursue every one of these cases,” he said. “These cases go on there quicker than we can get to them.”
It is no small task to conduct the necessary background work and knock on someone’s door, Detective Brown said. A case that seems relatively low-risk will usually involve four officers. If it is considered more dangerous, it might take eight. The priority, he said, is on people newly added to the system, because they are more likely to be at the address listed.
The state Justice Department’s firearms bureau does have a small unit, with 20 agents, that tracks down people on the list. Last year, it investigated 1,717 people and seized 1,224 firearms.
The list is growing far faster, however, than names are being removed. “We’re just not a very big bureau,” Mr. Lindley said. “We do the best we can with the personnel that we have.”
The bureau is planning a sweep this spring focused on people on the list for mental health reasons. Last summer, a man from the Fresno area who had recently been released from a mental health facility was found to possess 73 guns, including 17 unregistered assault rifles.
In the case of Mr. Perez, Lieutenant Cowan, of Baldwin Park, said he learned that state agents had been scheduled to visit Mr. Perez to confiscate his weapon — two weeks after the rampage took place.
