By Charlie De Mar

(CBS) – Questions have surfaced about the Chicago-based security company charged with keeping people safe at this Sunday’s Bank of America Chicago Marathon.

The security company,  known for its red windbreaker-wearing employees, lost its contract with the Minnesota Vikings and its Minnesota security license, CBS 2’s Charlie De Mar reports.

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Along with the Chicago Marathon, Monterrey Security works at a number of major venues across the city, including Soldier Field. The company has gone the past 10 years in Illinois without a negative citation.

Monterrey, however, just lost its contract with the Vikings, who have a brand-new stadium.

It is alleged the company double-billed the team and failed to properly do background checks and train employees — and hired workers with criminal records.

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Minnesota’s licensing board recently grilled Monterrey’s CEO, Juan Gaytan, Jr., who denied wrongdoing.

Chicago Marathon organizers say they are satisfied with the security firm’s explanations to officials here.

“Our operations team asked for a comprehensive explanation from Monterrey when we learned of the Minnesota situation, and we were satisfied with their response,” a statement issued Thursday said.

Last year at Soldier Field, two Monterrey security guards were arrested for selling stadium access wristbands to undercover officers before a Bears game. One of those security guards was later acquitted. Both men had previous criminal records.

They were later fired, but Monterrey’s CEO said he will continue giving people second chances and hiring former convicts.

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Some 40,000 athletes are expected to participate in this weekend’s Chicago Marathon, which is the 40th. One million spectators will watch along the route.

Charlie De Mar