That stands for Another found Dead.

Six candidates from Germany’s rightwing AfD party die 13 days apart in lead up to local elections: reports – Four candidates and two reserves from the right-wing AfD political party in Germany have dropped dead within 13 days of each other — just before elections, according to reports.
The Alternative for Deutschland candidates were set to appear on ballots in North Rhine-Westphalia on September 14.
Officials said no foul play is currently suspected in any of their deaths, the BBC reported.