The United States Postal Service has become the latest target of criminal organizations looking to recruit workers to help them boost checks and credit cards as well as move drugs around the country.

A recent federal investigation by the USPS Office of The Inspector General uncovered at least 12 mail sorting facilities operated by the USPS had a percentage of employees involved in numerous theft rings, according to the Dallas Morning News. Just last month, federal prosecutors charged two postal workers from Virginia and North Carolina, alleging that combined they stole more than $1 million in business checks.

“[Postal workers aren’t] getting a job because they want to deliver the mail, or they want to sort mail. They’re getting a job to steal mail,” Postal Police Officers Association President Frank Albergo said in an interview with WTKR at Norfolk, Virginia.

“Criminal organizations are recruiting postal workers to infiltrate the postal service. That should be shocking to everyone.”

The investigation uncovered that employees were stealing business and personal checks, credit cards, and even greeting cards that contained gift cards to various stores. They also discovered postal workers using the USPS system to traffic narcotics.

“Criminal organizations are targeting, recruiting and colluding with postal employees to move narcotics through the postal network and to steal checks — both personal and government-issued checks — credit cards and other valuables from the mail,” USPS Inspector General Tammy L. Hull is quoted as saying in the audit report.

Among the incidents recorded by investigators:

One clerk from Milwaukee specifically targeted greeting cards for the gift certificates they contained and was alleged to have stolen over 1,200 pieces of mail, placing them in a tray until the end of their shift when they would transfer them to a personal backpack on the floor before leaving the facility.

A mail handler assistant at a Kearny, New Jersey, facility was taking envelopes containing credit cards and placing them in her jacket and purse.

A group of seven mail handlers in St. Louis rifled through 150 packages, a third of which contained marijuana and cannabis oil. They would conceal the drugs in their backpacks and jackets and provide lookouts for each other as they removed them from the loading dock.

The investigators urged improvements at the facilities, including increased employee training, a more assertive nationwide policy that would ban personal items like coats and bags from being on the processing floor, and updating nearly 20,000 cameras in facilities – many of which are no longer functional.

“Employee mail theft damages the Postal Service’s reputation and diminishes public trust in the nation’s mail system,” reads a summary of the report.