California is the only state using the Armed and Prohibited Person System, a tool used by law enforcement officers to help seize legally obtained guns from felons, the mentally ill or someone who poses a risk to public safety. (Video: Ashleigh Joplin, Jorge Ribas/The Washington Post)

AZUSA, Calif. — By the time Senior Special Agent Sam Richardson’s team rolled up to the small house on Lark Ellen Avenue in a cool twilight, it had little to show for several hours of work.

The stops in San Dimas and Covina: no luck. At the gray house on a corner in Pomona, yes, Nohemi Page was home with her infant. But the four pistols registered in her name — guns that felony convictions in California now rendered illegal for her to possess — were long gone.

When Page went to drug rehab, her aunt placed her belongings in a storage unit, then stopped paying the monthly fee. The guns, as elusive as quicksilver in a country awash in weapons, now belonged to whoever bought the contents in a blind auction.

But the “knock and talk” at the house here, with Brenda Rivera, a 56-year-old grandmother with a felony theft conviction and a registered firearm, spun out differently. After a confused but calm hour and a half, the team had its first tangible success of the day. A pistol, the magazine missing. A hard-won trophy for a unit at the sharp, streetside edge of America’s debate over who should own guns and who should not.

“One more off the list,” Richardson said.

Five states allow guns to be seized before someone can commit violence

A broad, bald Tennessean, Richardson runs a six-person team of California Justice Department agents who are coming for your guns, but only if you no longer have the legal authority to own one in this state that has tightened firearm laws in increments over the years.

His division is the only law enforcement agency in the country assigned specifically to track down and take guns from felons, the mentally ill and others whose Second Amendment rights have been curtailed in court because of public safety concerns. That is, the people who even the National Rifle Association says should not have guns, a statement echoing in the aftermath of the mass shooting at Marjory Stoneman Douglas High School in Parkland, Fla. The program makes California’s gun-control policy perhaps the most aggressive in the nation.

A dozen years ago, the state set up a database that flags law enforcement officials when a registered gun owner is convicted of a felony, deemed mentally ill, has received a restraining order or committed one of about 37 qualifying misdemeanors.

The list is known as the Armed Prohibited Persons System, and while it has failed to prevent mass shootings in San Bernardino, Isla Vista and other cities in the state, it has taken tens of thousands of guns out of the hands of people prohibited from having them.

State officials say the kind of restraining order that a family or law enforcement official is allowed to seek here against someone of concern might have landed Nikolas Cruz, the alleged school shooter in Parkland, on the list if one existed in Florida. That will never be known.

The work of Richardson’s agents is overwhelming, with the number of guns and “prohibiteds” growing faster than the underresourced teams can take them off the street. So is the ingenuity of those selling guns, and those making guns, and those owning guns, legally or not.

There are 10,226 people on the list statewide. Of those, about 2,000 are in Los Angeles County, a vast urban desert covered by only Richardson’s team and one other.

Last year, state Justice Department agents seized 3,999 pistols and long guns, investigating more than 8,500 people in the process. The list has never dipped beneath 10,000 people since its earliest days.

“All of this takes time and real resources,” said Xavier Becerra (D), California’s attorney general, who said he is requesting more money for the program this year. “As quickly as we get these guns off the street, others are getting guns.”

Fla. school shooting creates urgent push for gun control, bipartisan calls for change

There are many reasons for the slow progress — the lack of resources; day-round traffic that requires agents here to target people on the list in geographic clusters rather than urgency; and legal checks. Simply because a person is on the list does not give state agents a right to seize the gun, only to ask permission to do so. If denied, agents must wait for a warrant.

There also are big victories. Last week, Richardson’s team went to the Temple City home of Steven Ponder, a 57-year-old convicted more than a decade ago of counterfeiting — and owning a machine gun. He had four guns registered in his name.

After being invited inside, the team found and seized 28 firearms, including 11 homemade “ghost guns” that carry no serial number, and 65,000 rounds of ammunition. One of the “ghost guns” was fully automatic.

Those days are rare. Eight hours with Richardson’s team along suburban cul-de-sacs, in chaotic garages and cluttered bedroom closets here in the San Gabriel Valley reveal the slow, delicate work that often yields little but a forwarding address or the certainty that a gun on the list will never be found.

But in the sometimes immeasurable way gun violence ripples through this country, even small victories could translate into a life saved, a crime prevented.

“We certainly believe we’re making a difference on crime,” Richardson said. “But it’s a drop in the bucket on the overall number of guns in circulation.”

The team recently began competing to see who can lose the most weight. In the lunchroom at the office-park field offices, the usual fast-food menu was replaced by healthy leftovers from home. At least, for some members of the team, which regularly puts in 20 hours of overtime a week.

“I wish I had the Popeye’s fried chicken right now, but the Panda will do,” said Special Agent Coseglia, a native of Flint, Mich., while looking down at a plastic tray full of stir-fried noodles.

The team is from various parts of the country and from various backgrounds. But they share years of experience in the field, a key to success in a unit whose way of working with potentially dangerous, unstable people emphasizes diplomacy over force.

Not once has a target fired on them. As this fact was noted, they reached for wood to knock on.

But they are threatened — some extreme gun rights websites seek to identify them and expose them online — so all except Richardson, who has appeared publicly, spoke to The Washington Post on the condition that only their last names be used .

“We don’t have black helicopters, but we drive black cars and wear black uniforms,” Richardson said. “It plays into the mind-set of some of these people.”

Into the field

Around 2 p.m., the team heads out in a trio of black cars, no license plates, and a minivan with a lockbox in back to hold evidence. On a breezy Wednesday afternoon, the Los Angeles sky is clear of haze. As the group heads east, the sun lights up the San Gabriel Mountains before them.

The distances are long, and the team hopes to get to eight addresses before calling it a night. The first one turns up nothing.

At the second address, the 10-year-old daughter of Marland Reed, convicted in Arizona of aggravated drunken driving, answers Special Agent Torrez’s knock. Her father, she says, isn’t there.

“At least we have a confirmed address,” says Torrez, who also predicts that the daughter will call her father, who will call the San Dimas office of the Los Angeles County Sheriff’s Department to find out if they visited his home and why.

Five minutes later, Richardson’s cellphone rings.

“Oh, we’ll look into,” he says. It is a sheriff’s deputy, as predicted. The state agents do not share their operations with local law enforcement officials. But they do coordinate with the regional “war room,” which serves all agencies, to avoid stepping on other cases.

The third stop, though, raises a strain of uneasiness that the team has about the list.

As Richardson heads for the Covina home of Benjamin Barreto, a 56-year-old with three registered guns, he points out that the “prohibited” man had not been convicted of a crime. He has several infractions, including driving without a license. Barreto is on the list because a judge said he could not possess a gun.

“The system captures a lot of people, and it’s probably better to capture all of them than none of them,” he says. “But it’s important for us to go after those who really matter.”

The house where Barreto is supposed to be living appears empty. But it is monitored by video technology, which has made the agents’ job harder, serving as an early warning for those inside or who are about to return home. The cameras can send a feed to an owner’s cellphone.

Agents fan out to talk to neighbors, who say they think that Barreto has moved to Riverside, a bordering county. The case will be sent to Richardson’s counterparts there.

His name and guns stay on the list.

Confusion, then a gun

A half-hour later, along Lark Ellen Avenue in Azusa, the team’s luck begins to turn.

The house where Brenda Rivera is believed to be living has a hammock strung between a pair of trees in the front yard. Several of the agents gather in the driveway, which leads back to a second house and a garage. Rush-hour traffic slows along the four-lane street as drivers try to get a glimpse of what’s going on.

A Nissan SUV pulls up to the sidewalk. The driver gets out and approaches the agents. A young girl in the passenger seat also steps down from the car carrying a backpack. She walks past the agents to the house in the back.

The man is P.J. Morella, Rivera’s son-in-law. The girl is his daughter Kristin — Rivera’s granddaughter — who has just returned home from winning the district basketball championship at Las Palmas Middle School.

“It’s never good having the cops here,” Morella says and laughs nervously. “But nothing surprises me anymore.”

Morella calls Rivera, who is effectively homeless and has been “couch surfing.” She tells him that the pistol registered in her name should be in the garage. Then Morella corrects her. “You sold me that gun years ago,” he says.

Surprised, two agents head off with Morella to get the gun from his nearby house. Richardson also has Morella’s name checked against the prohibited list. He comes up clean. With Rivera’s permission, they work to get into the garage to search it.

Torrez tries to pick the deadbolt lock. “It’s not as easy as the movies, that’s for sure,” said Special Agent Rodriguez. “It never just clicks open.”

About 20 minutes later, Rivera’s daughter and Morella’s estranged wife, Genevieve, arrive from her work as a billing agent for a life insurance company. She owns the house.

“This is so embarrassing,” she says repeatedly, as she opens the garage.

“My mother and I have never gotten along,” she says. “She lives her life, but I never agreed with it.”

A small dog barks behind a fence next door. From inside the house, several of Morella’s four children watch the agents, who pass out stickers displaying the state Justice Department emblem to them and to the neighbors’ kids. A TV set flickers with cartoons from a window.

The garage is packed to the rafters, and agents begin pulling out plastic house plants, a punching bag, an air mattress. A Dodgers banner hangs barely visible from high on the back wall. There’s nothing of interest.

P.J. Morella, though, has produced the gun the agents came for. The ammunition is gone. The gun comes off the list about 90 minutes after the agents had arrived. It will be taken back to the evidence locker, and if the owner does not make a legal claim for it, the gun will be destroyed.

“From our perspective, mission accomplished,” Richardson says. “But the process was a yawn.”

Ammo and an arrest

Five hours, one gun.

Before heading to a new address, the team circles back to the home of Marland Reed, whose daughter had answered the door a few hours earlier. The neighborhood is now illuminated by streetlights. Reed’s neighbor packs a bag full of baseball gear and her son into a BMW, pulls out for evening practice and asks whether everything is okay.

Reed is home. He tells agents the gun they’re seeking has been missing for years, but he has some ammunition in the garage that he took from the home of his recently deceased mother. Ammunition, even without a gun present, is illegal for him to have.

Coseglia explains to Reed that he is being arrested.

“I can barely breathe,” Reed says. “I’m shaking. . . . I have gotten beyond all of this, and I have sworn to my family they would never see me in handcuffs again.”

“I didn’t know this was a problem or I never would have told you to get it from the garage,” he tells Coseglia. “Now this is going to ruin my life.”

“It won’t ruin your life,” Coseglia says.

Reed is wearing sneakers and a sweatsuit. Coseglia asks if he has sandals and clothes that do not have drawstrings. To prevent suicide attempts, those items are prohibited in jail.

“We want to get him in and out as soon as possible,” Rodriguez tells Reed’s wife, who is pregnant. She will be able to post bail in the morning.

Minutes later, agents tuck Reed into the back of Torrez’s car. They had seized 350 rounds of ammunition from Reed, and it would be up to the local district attorney to decide whether to pursue charges.

The arrest highlights another concern state agents have about the list: While ignorance of the law is no excuse, people often don’t know they are on the list or what the restrictions are.

“The concept is a good idea, but we know that when the government goes to implement a good idea, it doesn’t always remain one,” says Craig DeLuz, a spokesman for the Firearms Policy Coalition, a gun-rights group in Sacramento, who thinks that people on the list should receive annual warning letters. “The biggest concern we have is how the list is administered.”

Discovery in a crowded closet

The next visit takes Richardson and Special Agent Powell into the bedroom closet of Tammy Luu, who arrived in the United States more than four decades ago by boat as a refugee from Vietnam.

Luu answers the door, and Coseglia asks if her son, Chris, is home. No, Luu says, he lives with his girlfriend. But she will call him.

Chris Luu had been convicted of theft in Arizona a few years ago, and entered a drug rehab program soon after. Agents had been tracking a pistol registered in his name.

She tells Coseglia she found it in his room after his arrest, and she hid it in the bottom of her closet. “It’s upstairs,” she says.

Photos of her husband, who had been brought to the United States during the Vietnam War to train with the Air Force as an F-5 pilot before fighting for South Vietnam, hang from her living room wall. He died 13 years ago, before Chris got into trouble.

Within minutes, Richardson is doubled over in Tammy Luu’s closet as piles of shoe boxes and dresses on hangers obstruct his search. “Are you sure he didn’t come back for it?” he asks.

Powell takes over the search, and when he pulls out a Tommy Hilfiger bag from the back, Luu signals that is the one. Inside is a gray plastic bag, and inside that a gray plastic box, and inside that a Heckler & Koch 9mm pistol.

There is no ammunition.

“I threw it away, right away,” she tells Richardson, who advises that, if there is a next time, to please save it and call the police to dispose of it. But the gun comes off the list, as does Chris Luu’s name.

When Coseglia hands Tammy Luu the receipt for the gun and tells her that she might have rights to it, she waves him off.

“I don’t want it,” she says.

Grinding away

The final stop is in Whittier, at an apartment complex where 24-year-old Ricardo Ramirez lives with a firearm. The team arrives, and Ramirez answers the door.

Something surprising happens. He has recently sold the gun, he tells agents, and on his iPhone he has pictures of the proper transfer papers.

Everything is in order. The gun comes off the list.

Eight hours, three guns off the list, 350 rounds of ammunition seized, one arrest.

“Three people out of the database in three different ways,” Richardson says. “A lot of this is just pounding the pavement, grinding away at the list.”