When we think of crime labs, we often think of shows like CSI or NCIS in which flawless technicians rigorously employ scientific methods in pristine labs. We don’t usually think of people faking test results, contaminating samples, or forging signatures. Nor do we think of dirty equipment, faulty techniques, or a lack of standardized procedures. But it happens more often than we care to believe. This report reviews the astonishing problems that persist in some crime labs across the country and that have caused mayhem in the lives of people we charge, convict, and sometimes, kill for alleged crimes.