The murder of Minnesota Democratic state lawmaker Melissa Hortman and her husband, Mark, in June. An arson fire at Pennsylvania Gov. Josh Shapiro's house in April. The shooting death of UnitedHealthcare CEO Brian Thompson on a New York sidewalk in December. Before that, the hammer attack that nearly killed Nancy Pelosi's husband, Paul, at their San Francisco home, and two attempted assassinations of President Trump. The events have shaken people on the left and the right.