Two regional government officials from the state of Rhineland-Palatinate are suspected of causing another person's death and causing bodily harm through negligent action following the heavy floods in mid-July that killed 141 people in the state.
Slow evacuation
The initial investigation by the Koblenz Public Prosecutor's Office has raised suspicions that evacuations have been delayed.
According to a survey commissioned by the German newspaper Bild, two-thirds of Germans believe that decision-makers at both the federal and regional levels should have done more to protect society.
Across the country, more than 170 people died, thousands of homes were destroyed and many still do not have electricity and water.
Received 25 weather warnings
Prosecutors in Liège, Belgium, have also launched a criminal investigation into media reports that Belgian authorities acted only at the last minute, despite receiving 25 weather warnings.
"We want to investigate the truth in peace and quiet, objectively and independently, out of respect for the victims and their families," prosecutor Damien Leboutte told international media.
A total of 37 people lost their lives in the province of Liège.