Atlanta police arrested four Department of Public Works employees today on charges of theft, the latest effort in the city’s quest to root out suspected pervasive corruption.

An official within Mayor Kasim Reed’s administration said the employees, Edward Earl Childs, Oscar Dawson, Ricardo Dupree and Len Antonio Goggins, Jr., are suspected of taking metals, including copper, from the department’s Claire Drive location and selling it to a recycling plant.

Childs, Dawson and Dupree were arrested at a Public Works facility on Monday. Goggins was arrested at a separate location, officials said.

Chief Operating Officer Michael Geisler is expected to address the media with additional details about the investigation this afternoon.

The arrests come one week after authorities took two Department of Watershed Management employees into custody on similar charges. Police say those men, Charles Edwards and William Spaulding, sold city-owned pipes and scrap metal to recycling centers over the course of several years.

According to a police report, last week’s Watershed arrests resulted from an investigation conducted by an employee of the City Auditor’s office who tracked down receipts for the missing equipment.

Last fall, City Auditor Leslie Ward warned councilmembers about concerns that the city lacked adequate controls for tracking its equipment. In August, she presented an audit that found the Public Works department couldn’t account for at least $2.2 million in materials, such as asphalt, lacks critical inventory management controls and is vulnerable to undetected theft.

Ward also released a damning audit of the Department of Watershed Management, which has received the brunt of criticism in recent years after hundreds of thousands of dollars in equipment, such as 28 industrial water meters and an $80,000 backhoe, went missing or was reported stolen.

Ward’s audit found Watershed also couldn’t account for more than 10,000 water meters. Ward’s office also found lax security at several Watershed facilities, including keys left in locks.

Watershed Commissioner Jo Ann Macrina has laid out steps the department is taking to tighten its security, including requiring manager sign-off on equipment check-out, limiting who can order, receive and distribute equipment, and monitoring security-camera feeds from a central location. Watershed also will implement a bar-code system to track its equipment, worth a total of about $20 million.

The arrests come just weeks after Atlantans approved an infrastructure bond worth $250 million to fix the city’s aging roads, sidewalks and buildings. The Public Works department is largely charged with overseeing the construction.