Alice Weidel, the parliamentary group leader of the far-right Alternative for Germany (AfD) party, is being formally investigated for violating campaign finance laws, the public prosecutor’s office in the southern city of Konstanz announced Tuesday. The AfD branch in Lake Constance is accused of receiving large sums of money from a Swiss company in the leadup to Germany’s 2017 general election. The vote saw the AfD become the largest opposition party in the Bundestag. The donations from abroad, paid in 18 tranches, reportedly amounted to more than €132,000 ($150,000). The prosecutor said the probe would target Weidel and three other...