Monterrey Security, the Chicago company that protects U.S. Bank Stadium, is under investigation by a state board.

Minnesota Sports Facilities Authority (MSFA) Chairwoman Kathleen Blatz said Thursday stadium management is trying to figure out when the Minnesota Private Detective and Protective Agent Services Board will complete the investigation purportedly into Monterrey's hiring practices.

Citing unidentified sources, KSTP-TV reported that the investigation into Monterrey involves falsification of government documents, failure to conduct adequate background checks and hiring people with felony convictions without getting proper clearance. The station said the investigation involves hundreds of employees.

"It's one thing to make allegations, it's another to have evidence," said Blatz, a former state Supreme Court chief justice.

Monterrey Security is in the first year of a three-year contract to provide round-the-clock security at the new $1.1 billion stadium. The company was chosen in a competitive bidding process. Monterrey also provides security for the NFL's Chicago Bears and the NHL's Chicago Blackhawks. The company runs security for the Chicago Cubs, the Chicago Marathon, soccer games and concerts from the Grateful Dead to Kenny Chesney.

Stadium security was breached in the final game of the Minnesota Vikings season Jan. 1 when two protesters were able to drop down from the scaffolding to unfurl a banner protesting a pipeline. Security will continue to be a significant concern in the 66,200-seat building set to host the Super Bowl in February 2018.

Monterrey has 3,500 employees and is the largest Latino-based security firm in the Midwest. President and CEO Juan Gaytán Jr. founded the company in 1999.

The next MSFA meeting is set for June 22, but Blatz said no action against Monterrey is planned. "I don't know what they've got to back it up," she said of the investigation. Then, citing Monterrey's contracts for stadiums and events across the country, she said, "I would assume they know what they're doing; I can't believe it's just wholesale neglect of the rules."

In a written statement, SMG, the stadium's operator said, "We expect that Monterrey Security will cooperate fully with state officials for the ongoing investigation. Upon the completion of this investigation, SMG will take appropriate action. ... The safety and security of all guests and employees of U.S. Bank Stadium continues to be our top priority."

Greg Cook, director of the state board, said he couldn't comment. Monterrey Security's Chicago office didn't return a call.

Twitter: @rochelleolson