ATLANTA - In the latest sign that she is moving rapidly in her investigation into Donald Trump’s efforts to overturn the 2020 election, Fulton County, Ga., District Attorney Fani Willis has sent so-called target letters to prominent Georgia Republicans informing them they could be indicted for their role in a scheme to appoint alternate electors pledged to the former president despite Joe Biden’s victory in the state, according to legal sources familiar with the matter. The move by Willis, a Democrat, could have major political implications in a crucial battleground state with high-profile races for governor and the U.S. Senate...