A former city of Philadelphia employee faces up to 20 years in prison after pleading guilty to counterfeiting more than 2,000 monthly SEPTA passes.

Mark Cooper, 35, pleaded guilty Monday to his involvement in a conspiracy that fabricated fake SEPTA passes and sold them for $50 each, instead of the $91 for a genuine TransPass, primarily to municipal employees around City Hall, U.S. Attorney Zane David Memeger announced.

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Cooper, who formerly worked for Philly 311, the city’s call center, made the fake SEPTA cards using equipment he allegedly ordered from Amazon, Philly.com reported.

Kimberly Adams, a co-conspirator who pleaded guilty to her involvement in 2015, was scheduled to be sentenced on May 18, the U.S. attorney’s office stated.

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With Cooper’s guilty plea on Monday, he now faces 20 years in prison, a fine of up to $500,000, four years of supervised release and a $200 special assessment.