Part 4 of a series examining Cook County property taxes, by Jason Grotto and Sandhya Kambhampati, includes “State law says the assessor must revalue property every three years. Yet Berrios, using methods hidden from the public, repeatedly produced initial valuations of commercial and industrial properties — known as first-pass values — that did not change. … Berrios already is under fire for producing inaccurate residential assessments that burdened poorer homeowners …'They are not doing an accurate job of assessing property, and I think it’s a frustration for everyone … It means time, effort and money because they make you hire lawyers to appeal inaccurate assessments.' …”