CHICAGO (CBS) — Arrest warrants have been issued for at least four people in connection with the theft of more than $870,000 from Chicago Public Schools.

According to a CPS inspector general’s report, this is part of a larger theft scheme that is connected to seven people who have worked for Chicago Public Schools.

Arrest warrants have now been issued for some of those employees accused of submitting fake invoices for hundreds of thousands of dollars in work that was never done, or offices supplies that were never purchased.

The CPS inspector general said, in one case, a business owner kicked back more than $111,000 to a CPS employee in return for more than $216,000 in business, most of which was fraudulent.

To quote the inspector general’s report, that means the business owner and the CPS employee “essentially stole the money and split it between them.”

CPS records show three people involved in the alleged scheme, Sidney Bradley, Albert Bennett and Paul Simmons, owned companies that last month CPS permanently banned from doing any further business with them.

Court records show Bradley and Bennett are accused of stealing the bulk of the government money.

“There was no oversight and not enough people have been held accountable. That’s the real problem. These things are always going to happen, but people have to be watching to catch them sooner than five years,” said Better Government Association President and CEO Andy Shaw.

Asked how something like this happens, Shaw says, “It’s human nature. There’s always going to be scammers. The problem is, no one discovered it.”

A CPS spokesman issued a response saying, “Keeping our resources in the classroom is essential to help students and teachers continue to make academic gains. While we cannot comment on this ongoing investigation, CPS has already taken proactive steps to prevent any similar incident from occurring in the future.”