WASHINGTON - Officials in the federal agency that oversees American Indian trust assets had an improper social relationship with an accounting firm and pressured subordinates to give the firm preferential treatment, a government investigation found. Senior managers in the Office of the Special Trustee for American Indians based in Albuquerque, N.M., golfed, drank and partied with the executives of the New Mexico accounting firm Chavarria, Dunne & Lamey, which won $6.6 million in contract work over eight years, according to the report by the Interior Department's inspector general. The investigation, first reported this week by U.S. News & World Report,...