HUMBLE, Texas -

Four grocery store employees have been charged with theft after managers discovered the team approving tens of thousands of dollars in unauthorized coupons, detectives said.

Police said Krystal Cormier, Cory Lester, Traveon Boyd and Latrisha Wilkerson worked at the Humble Kroger at Highway 59 and 1960. Between July 20  and Oct. 16, the foursome worked with customers to defraud the store of $69,987.03, investigators said.

"These employees had been using a coupon override code and were accepting payment from certain customers to do this," Humble Police detective David Scott said. 

Scott said that when those customers came through their line, they would hand the cashier a load of coupons that didn't even match the items they had purchased. By hitting a coupon override code, the system accepted the coupon and it allowed the employee to change the amount the coupon was worth. Scott said the foursome routinely punched in $10 off for each coupon the customers presented.

"At the end of their total transaction, their bill would be 94 to 95, sometimes 96 percent off what the bill should have been, and then they were paying the employee a tip for that service," explained Scott.

That's where the pay off came for the employees. Scott said they were paid up to $100 every time they checked out the customers with what should have been worthless coupons.

It was Kroger's own loss prevention department that spotted the thefts and did most of the investigation before handing it over to police.

"As a company, we take organized retail crime seriously," A Kroger representative wrote in a statement. "The associates involved have been terminated and charged with felony theft.

"The safety and security of our customers and associates is of the utmost importance. We review store procedures and protocols on a regular basis to ensure up-to-date practices are in place to deter theft. Our staff is working diligently with local authorities regarding this investigation and plan to prosecute to the full extent of the law."

As for the customers who presented the worthless coupons, the investigation is ongoing. Police said they believe there were many people involved and they haven't been able to identify everyone. 

Police said they believe this same kind of scheme is going on in stores in and around the Houston area. They said more arrests are pending.