Following his trip to Washington and marriage, Daveiss received an appointment as United States Attorney for Kentucky. In February and March 1806, as U.S. Attorney, he wrote President Thomas Jefferson several letters warning him of possible conspiratorial activities by Aaron Burr, who at that point was a former vice president of the United States. Daveiss' July 14 letter to Jefferson stated flatly that Burr planned to provoke a rebellion in Spanish-held parts of the West in order to join them to areas in the Southwest to form an independent nation under his rule. Similar accusations were appearing against local Democratic-Republicans in a Frankfort, Kentucky newspaper, Western World, and Jefferson dismissed Daveiss' accusations against Burr, a Democratic-Republican, as politically motivated.
