Southern California police agencies regularly lose track of all manner of firearms, from high-powered rifles and grenade launchers to standard service handguns – weapons that often wind up on the street.

An Orange County Register investigation of 134 state and local police agencies from Kern County to the Mexican border found that over the past five years at least 329 firearms were lost by or stolen from law enforcement agencies.

Dozens of these weapons wound up in the hands of criminals – and some were involved in crimes. In Northern California, a missing police gun was used in a suspected murder.

But the number of guns known to be missing or stolen is almost certainly a fraction of the actual number that have made the jump from police agency to street. Not every department audits its weaponry. If agencies performed such audits, they’d find they were missing more guns.

That was the case at one of the biggest police agencies in the country.

The Los Angeles County Sheriff’s Department, following a request by the Register, assembled a team of nearly two dozen employees to track through thousands of files on gun location and gun assignments. The research found that at least 103 L.A. County Sheriff’s Department guns, ranging from service handguns to shotguns, were lost or stolen over the past five years.

A spokesperson said the agency didn’t previously know how many guns were missing, and hadn’t recently conducted a centralized count of its service handguns. The missing weapons are a tiny portion of the department’s 20,000-gun arsenal.

NOT A PRIORITY?

But the Los Angeles County Sheriff’s Department isn’t the only big police agency to conduct an audit and learn that it has lost a lot of guns.

In recent years, police departments in Oakland and San Jose counted their weapons, and each found more than 300 service firearms had vanished over a six-year period, according to a report and database from Southern California News Group’s sister publications in the San Francisco Bay area.

The number of guns missing isn’t always a high priority.

At least 24 agencies contacted over the past three months didn’t respond to requests for data on missing or stolen weapons. And the Long Beach Police Department, one of the bigger agencies in Southern California, said it doesn’t track weapons because its officers provide their own guns.

That’s not true at every department. Some of the biggest proponents of police counting and tracking their weapons are, in fact, police chiefs.

In Hermosa Beach, the Police Department conducts an internal audit of its armory every year, tracking serial numbers of weapons, matching them with the officers who use them, and listing any weapons that have gone missing over the previous year. The department hasn’t lost any guns, nor have any been stolen, according to agency records.

It’s a policy that’s been in place in Hermosa Beach for years, and was supported by Police Chief Sharon Papa when she came to the force two years ago.

“I’m just thrilled that we have our annual audit and we didn’t run into problems other agencies have,” said Papa, a former assistant chief at the Los Angeles Police Department.

Tracking weapons, Papa added, “just isn’t a regulated area” for police.

“So, they don’t think about it.”

NO LAW TO FOLLOW

What are the differences among police agencies when it comes to tracking guns? Choices.

There are no state or federal laws requiring police agencies to account for their firearms. Any agency that conducts a gun count or sets formal rules for how officers store and carry weapons is doing so voluntarily.

Likewise, there is no requirement that individual officers or deputies tell anybody, including any state or federal agency, when their weapons are lost or stolen. Instead, police agencies voluntarily report missing weapons to a database kept by the state.

Also, on- and off-duty police officers are allowed to store and carry weapons in ways that would be unlawful for other citizens in California. The theory behind that law is to make sure an officer doesn’t have to unlock a stored gun to use it in an emergency, but in practice it often leads to police guns being stolen.

It’s also unclear what happens to officers who lose their weapons. The internal reports from police agencies didn’t include gun-related reprimands, if any were issued, because the information is considered a confidential personnel matter.

There are about 300 million guns in America, and nobody knows how many are owned or controlled by police agencies. What is known is that it’s not rare for police and their weapons to go separate ways and that, in general, lost or stolen police guns account for some of the weapons used to commit crimes.

“A significant source of guns in illegal hands, on the black market, come from stolen firearms,” said Ari Freilich, staff attorney with San Francisco’s Law Center to Prevent Gun Violence.

“We should be concerned that police – and all individuals that keep deadly weapons – know where their guns are.”

LOST OR STOLEN

Glocks, Sig Sauers, Remington shotguns, rifles, even grenade launchers – all these and more were reported lost or stolen from police inventories or individual officers.

In all, Southern California agencies said at least 108 of the missing firearms were reported stolen by their officers.

At least 22 of the stolen guns were retrieved. Authorities in Mexico recovered some guns stolen from U.S. law enforcement, while U.S. police found other weapons in the hands of fleeing felons.

Often, the reports show, officers treated their guns in ways that wouldn’t be legal for most civilians. High-caliber firepower was stowed in backpacks or gym bags and stuffed behind car seats. Handguns were stashed in center consoles or glove boxes. Burglars looking for weapons that on the street can be sold for several hundred to a couple of thousand dollars found them.

In January, an Irvine Police sergeant slipped his .45 caliber Sig Sauer into a computer bag on the passenger seat of his unlocked Chevrolet cargo van, parked in the driveway of his Laguna Niguel home, according to a sheriff’s report. He returned to find the bag gone, gun and all. The handgun was found that same night after two men ditched the bag at a gas station.

In April 2013, an Irvine reserve officer stored his service weapon in the center console of his Ford Expedition before spending the day at Shapell Park in Yorba Linda. He returned to find the gun missing. There were no signs of forced entry, which can sometimes mean the vehicle was left unlocked, according to Orange County Sheriff’s Department officials.

In November 2015, an Orange County Sheriff’s detective left her 40-caliber service Glock in an unmarked department Ford Taurus outside her home. The gun disappeared – along with two magazines. There were no signs of forced entry.

A San Diego County Sheriff’s deputy left his 40-caliber Glock in his car outside his home in El Cajon in October 2012. The handgun was stolen and recovered a few days later from a fugitive parolee captured at the immigration checkpoint in Pine Valley.

Eighteen firearms were reported stolen from San Diego County deputies, including one assault rifle, which was later recovered. Two of the firearms – Glock 40-caliber handguns – turned up in Mexico, where authorities are holding both.

“It’s regrettable; we don’t like to lose our firearms,” said San Diego County Assistant Sheriff Mike Barnett.

“It’s a problem we are trying to deal with.”

Law enforcement officers – unlike most civilians – don’t have to follow state law requiring that guns left in unattended vehicles be locked in the trunk or secured in a locked gun box and placed out of sight. State Sen. Jerry Hill, D-San Mateo, has authored a bill now heading to the governor’s desk that would eliminate that loophole for police.

“(Guns) become such a part of their existence, that they may lose significance. It’s kind of like your cellphone,” Hill said.

“It’s carelessness, and it’s a lack of respect for the power of that weapon.”

There also is no state law requiring that police – or anyone else – report stolen firearms to authorities. Proposition 63 on the November ballot would make it mandatory for gun owners to report stolen weapons to police and for police to report their stolen weapons to their departments.

In California, guns that are reported as stolen or lost are voluntarily logged into the Automated Firearms System kept by the state Department of Justice.

BIG NUMBERS, BIG GUNS

Most, but not all, police agencies provide service weapons to their officers. Most agencies also replace lost or stolen weapons. Agencies can buy a handgun for prices starting at about $500 each, without a trade-in.

But the range of weapons that go missing runs far beyond handguns. The Register’s analysis found:

• The San Diego Police Department lost track of 30 firearms, including four rifles and 21 shotguns, most of which are used to shoot bean bags. Gun dealers point out that the bean bag guns can handle regular shotgun rounds, meaning they are potentially lethal if used on the street.

• About 10 high-powered weapons, including eight AR-15s and two M16s, were missing, stolen or lost from departments in Orange County, San Diego County, Riverside County, Pomona, San Gabriel, Desert Hot Springs and Carlsbad.

Two deputies, one in San Diego County and one in Orange County, separately left assault rifles worth $1,500 apiece on the trunks of their patrol cars and drove away. The Orange County deputy had put the rifle down to take a call on his cellphone, according to authorities. By the time the deputies realized what they had done, the weapons were gone. The California Highway Patrol found the San Diego rifle. The Orange County rifle remains on the streets.

• The Riverside Police Department early this year couldn’t find 26 firearms, including 17 shotguns. Ten shotguns and one training handgun still haven’t been located. Officials said the shotguns were lost because they are used by multiple divisions and were stored in different lockers. Also missing is a 40 mm launcher that can be used for anything from bean bags to grenades. The department is revamping how it counts and tracks its shotguns.

• The police department that patrols the Port of Los Angeles couldn’t find 11 firearms when it conducted a recent audit. An additional eight guns were stolen from its officers, including one taken from the home safe of a retired range officer. That officer told the department that he didn’t know he had the gun, according to a police report.

POTENTIAL FOR DISASTER

Weapons that are lost or stolen can lead to potential disaster.

Karen Steinle was killed last year while strolling on San Francisco’s Pier 14 by a man armed with a handgun stolen from the unsecured car of a federal park ranger.

When Costa Mesa police searched a motel room rented by a convicted drug dealer in 2012, they found a gun taken several months earlier from a car parked in the garage of a Yorba Linda home. The gun belonged to an Orange County District Attorney’s investigator. It was stolen from a bag behind the car’s front seat.

Two years ago, a San Gabriel officer locked his patrol car but left a window partially open outside Cheers Bar and Grill. That was opportunity enough for a drunken patron to shove his hand through the opening, unlock the door and yank an AR-15 assault rifle out of its rack, according to an internal report. Police later recovered the weapon at the man’s house.

VANISHED

It’s unclear if agencies would welcome regulations requiring regular gun counts, but some police leaders believe the profession could do a better job of keeping track of weapons.

“Obviously firearms are an important thing to safeguard,” said Ventura police Chief Ken Corney, who is also president of the California Police Chiefs Association. “It should be happening, whether or not there’s a state law.”

Some of the nation’s biggest police agencies agree, at least in part.

The Houston Police Department requires its officers to provide their own guns, and it doesn’t track those. But the department does conduct regular audits of every weapon it owns, including the assault rifles, shotguns and other firearms and equipment that go to its SWAT teams and others, said spokesperson Jodi Silva.

“They even count the damn chairs,” Silva said.

But even with strict gun counts, agencies wouldn’t always know why a gun goes missing. The Register’s analysis found many guns are lost with no explanation.

In Downey, the Police Department recently was unable to locate eight guns. Nearly all the officers assigned those weapons said they had turned them in. One said he left his gun in his locker when he resigned.

Gun experts say a general lack of oversight wouldn’t be tolerated in retail or manufacturing or any other level of the gun market.

For example, Chuck Michel, an attorney who specializes in gun laws, said if police agencies were gun stores, many would go “out of business for the way they keep inventory.”

“Every gun dealer is required to know where every gun … is at all times,” Michel said.

“Why aren’t these police departments holding themselves to at least these standards?”

Bay Area News Group investigative reporter Thomas Peele contributed to this report.