Ten former employees of the New Orleans Sewerage & Water Board are suspected of stealing tens of thousands of pounds of brass fittings from the agency and selling the metal to local scrapyards, city officials said Wednesday, describing a scheme that went undetected for at least two years and cost the city more than $500,000.

An investigation by Inspector General Ed Quatrevaux's office exposed an alarming lack of oversight at one of the city's biggest agencies.

The probe, which began in January, found that more than 34,000 pounds of brass intended for residential water meters had been stolen since 2013, resulting in a loss to the city of about $526,000. The employees earned just $41,000 by selling it.

The total amount of brass stolen would have been enough to install new water meters in more than 6,300 homes, said Howard Schwartz, a former FBI agent who heads criminal investigations for the Inspector General's Office.

Officials said they had not been tipped off to the thefts but detected the graft through the use of "computer analytics," a technique Schwartz declined to describe in detail because the investigation is ongoing.

He said investigators compiled "dozens and dozens and dozens" of photographs of the illegal transactions, the brass fittings and the employees who stole them. 

"There is no brass mine in New Orleans," Schwartz said. "There is only one place to get this, and it's the Sewerage & Water Board."

The scheme did not appear to be well organized, Quatrevaux said, even though the thefts increased significantly from 2013, when some 800 pounds of brass was stolen, to 2015, when nearly 24,000 pounds of the metal was sold to local scrapyards.

The authorities estimated that more than 40,000 pounds of brass would have been stolen in 2016 if the inspector general had not intervened. By law, scrapyards must require sellers to show photo IDs, which the employees in question apparently provided. 

"Word spread that this was a way to pick up some money," Quatrevaux said. 

All 10 of the employees implicated in the scam — Kenneth Webster, Keith Martin, Sam Johnson, Cedric Beaulieu, Darrin Robinson, Farid Mateen, Marlon Hughes, Darrell Fairley, Chester Rollins and Traivus James — were interviewed by investigators, and all have left the agency. Some of the employees were terminated, while others resigned or retired.

Arrest warrants for the employees were obtained Friday by Orleans Parish District Attorney Leon Cannizzaro's office, Schwartz said. They are expected to be booked on counts of theft of metals and malfeasance in office.

Cedric Grant, the executive director of the Sewerage & Water Board, said he is trying to change an internal culture at the agency "where people think that they can do things that they can't." 

"Needless to say, I'm shocked and appalled by the brazenness of the crimes committed," Grant told reporters. "My father used to tell me all you have is your integrity. So trust is everything."

The Sewerage & Water Board has taken several steps to boost security in the wake of the inspector general's findings. Among other changes, brass fittings will now be embossed with the water board's seal, marking them more clearly as government property.

The agency also has hired a new deputy director of security and is contracting with a new security firm to patrol its facilities. It also has installed new video surveillance systems and implemented quarterly warehouse inventories. 

"The old way of doing things is over at the Sewerage & Water Board," Grant said. "Under my leadership, we're building a new Sewerage & Water Board, one that has zero tolerance for theft of public property or any violation of the public trust."

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