LOS ANGELES >> The head of the Federal Bureau of Alcohol, Tobacco, Firearms and Explosives in Los Angeles has cautioned Southland police departments to watch out for the “growing trend” of law enforcement officers engaging in unlicensed, illegal firearms dealing.

In an advisory distributed to area police and sheriff’s departments and dated March 31, Special Agent in Charge of the ATF in Los Angeles Eric D. Harden warned that the agency has learned of an “emerging problem” with respect to law enforcement officers buying and then reselling guns, in possible violation of federal firearms law. The involved guns include many which are considered “off-roster” under California law, meaning that they can be purchased only by law enforcement officers and are not available to the general public.

“Recently, ATF has discovered that some law enforcement officers who do not have a (Federal Firearms License) are purchasing ‘off roster’ firearms and reselling those firearms to non-law enforcement entities for a profit,” Harden wrote.

Some of the weapons have turned up at crime scenes.

“In some instances, ATF has discovered officers who purchased more than 100 ‘off roster’ firearms that were subsequently transferred to non-law enforcement individuals,” Harden continued. “Such transactions potentially constitute violations of federal firearms laws, to include dealing firearms without a FFL, and lying on a federal firearms form when purchasing said firearm — also known as ‘straw purchasing.’ ”

Officials declined to provide details regarding the incidents described in the advisory.

ATF agents conducted a search at a Sierra Madre home of a Pasadena police lieutenant on Feb. 16. Officials reportedly seized numerous large gun cases from the home, though no arrests were made. Federal officials released no information about the raid, and Pasadena police have deferred to the ATF for comment.

ATF Spokeswoman Ginger Colburn said the agency could not discuss whether the February raid helped prompt the ATF advisory.

“As a matter of (Department of Justice) policy, ATF cannot comment on any ongoing investigation or confirm individuals involved,” she said.

The lieutenant remains on paid leave pending the investigation, Pasadena Police Chief Phillip Sanchez said. He declined to comment further.

The involved lieutenant has also declined to comment.

While individuals can sell personal firearms without a federal firearms license, anyone engaged in the business of firearms sales must obtain a federal license, Colburn said.

Harden also noted in the letter that filling out paperwork while purchasing a firearm to indicate the weapon for personal use while intending to sell it or otherwise give to someone else is also a federal crime for anyone, including law enforcement.

A conviction for dealing in firearms without a license carries a maximum penalty of five years in prison and a $250,000 fine. Making a false statement to a Federal firearms licensee when acquiring a firearm carries a maximum sentence of 10 years in prison and a $250,000 fine.

Harden’s advisory described the issue as a “growing trend.”

“ATF believed education is the most effective way to stop the growing trend of law enforcement officials engaging in the business of unlicensed firearms dealings,” Harden said in the advisory. “It is our goal to educate, not investigate, to ensure law enforcement officials comply with federal law in order to avoid unnecessary public embarrassment to themselves and your Department/Agency.”

But he added, “When presented with compelling evidence of flagrant violations of federal firearms laws, ATF is obligated to conduct a criminal investigation.”