Seattle police officers resort too quickly to the use of weapons like batons and flashlights, and escalate confrontations even when arresting people for minor offenses, because of inadequate supervision and training, the Justice Department said Friday in announcing findings from a seven-month investigation. The department began its investigation of the Seattle Police Department last spring after the fatal shooting of a homeless American Indian woodcarver in 2010 and other reported uses of force against minority suspects. The inquiry was aimed at determining whether the Seattle police have a “pattern or practice” of violating civil rights or of discriminatory policing, and if so, what they should do to improve. Federal investigators said they found that the Seattle police had engaged in excessive force that violated federal law and the Constitution.