Not long ago it was “common knowledge in certain circles” around the Twin Cities that car crash victims could pocket some extra cash if they went to the right person, a federal prosecutor told jurors Thursday in U.S. District Court in Minneapolis. As the first of multiple fraud trials involving metro chiropractors accused of bilking insurance companies out of millions of dollars got underway, jurors were quickly asked to consider whether they would be reviewing a case of doctors putting profit over ethics or merely the latest example of an intractable billing dispute between insurers and health care providers.