A U.S. Customs and Border Protection supervisory officer who worked at the Long Beach and Los Angeles port complex pleaded not guilty today to federal charges of unlawfully selling firearms without a license, including an illegal short-barreled rifle purchased by an undercover investigator.

Wei Xu, 56, of Santa Fe Springs, is accused of selling or otherwise transferring at least 70 firearms through a federal firearms license dealer since 2014. Court papers allege Xu exploited his status as a law enforcement officer to purchase and then transfer at least 14 “off-roster” handguns that cannot be sold to the general public.

Xu operated his business by posting advertisements on internet marketplaces, according to the U.S. Attorney’s Office.

According to an affidavit, an undercover law enforcement officer posing as a buyer purchased a total of four firearms from Xu, three of which were unlawfully sold out of the trunk of a car. Federal prosecutors allege the firearms included an “off-roster” pistol, high-capacity magazines, and a short-barreled rifle.

Federal authorities seized more than 300 firearms, including numerous assault rifles, two additional short-barreled rifles and what appeared to be machine guns from Xu’s home, according to the government.

If convicted of the charge of dealing firearms without a license, Xu would face up to five years in federal prison. The charge of possessing an unlicensed firearm carries a maximum of 10 years in prison, according to the U.S. Attorney’s Office.