As a battle-tested veteran of many political and legal wars, Minnesota Attorney General Mike Hatch knew a political torpedo when he saw one approaching. In February 2005, he thought he saw one in a Chicago resident's letter seeking records on how much Hatch office's spent on travel, furniture, artwork and outside lawyers. He traced the suspicious investigation back to a Chicago firm he said is known for doing so-called opposition research -- that is, digging dirt -- for Democrats. In time, he linked the probe to another top state DFL leader, Rep. Matt Entenza.