Chicago Most Corrupt City In Nation?

From the local CBS Chicago Radio affiliate:

A former Chicago alderman turned political science professor/corruption fighter has found that Chicago is the most corrupt city in the country.
He cites data from the U.S. Department of Justice to prove his case. And, he says, Illinois is third-most corrupt state in the country.
University of Illinois professor Dick Simpson estimates the cost of corruption at $500 million.
It’s essentially a corruption tax on citizens who bear the cost of bad behavior (police brutality, bogus contracts, bribes, theft and ghost pay-rolling to name a few) and the costs needed to prosecute it. . . .