SAN FRANCISCO (CBS SF) — U.S. Attorneys charged the heads of an Oakland engineering firm with bribery and connected them to a widespread corruption scandal in San Francisco’s Department of Public Works.

The Department of Justice (DOJ) announced Thursday that Alan Varela and Bill Gilmartin of Pipe and Plant Solutions, Inc. provided gifts and benefits to a city official beginning back in 2013. The two reportedly gave the official, former public works director Mohammed Nuru, $20,000 in meals and a tractor worth $40,000, among other items.

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In exchange for the gifts, the DOJ claims that Nuru gave Vareka and Gilmartin “a steady stream of illegal inside information about a lucrative San Francisco public contract” for building an asphalt recycling plant.

“Public works contracts in San Francisco are supposed to be awarded on a merit system in San Francisco for the benefit of the residents and taxpayers of San Francisco,” said U.S. Attorney Anderson. “The complaint filed today alleges that this merit system was undermined with insider information and favorable treatment.

In this March 19, 2015 photo, Mohammed Nuru, director of San Francisco Public Works, talks about the features of a public toilet at the Tenderloin Pit Stop as he is interviewed in San Francisco. Not far from the fancy stores of San Francisco’s Union Square, solar-powered flushing toilets on wheels roll in four afternoons per week in the dense Tenderloin neighborhood. (AP Photo/Jeff Chiu)

Varela and Gilmartin are the seventh and eighth defendants in a massive corruption case surrounding Nuru. Agents first publicized the case back in January, when it announced bribery charges against Nuru and local restaurateur Nick Bovis. Two other defendants with construction businesses, Balmore Hernandez and Florence Kong, indicated through paperwork that they planned to plead guilty, according to a DOJ press release. The filings indicate that Hernandez is cooperating with the investigation.

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“While our investigation is ongoing, I hope the resolutions in the Hernandez and Kong cases will help restore confidence in our city governments for Bay Area residents,” said assistant SAC Patel. “San Francisco City Hall can and will function without the influence of the corruption we have seen unravel in this case.”

Bovis pled guilty wire fraud and agreed to cooperate with the investigation back in May. Local contractor Walter Wing Lok Wong pled guilty to bribery in connection to the scandal in June.

The other former city official charged in the case is Sandra Zuniga, who used to be Mayor London Breed’s “Fix-It” Director. She was charged back in June along with Hernandez and Kong. 

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Varela and Gilmartin face a maximum statutory penalty of up to 10 years in prison, as well as fines that could go as high as $250,000.