The 65-year-old official, who became known as Mr. World Cup, shot himself in his home in a suburb of Berlin just hours after the tournament ended last Sunday. He was taken to hospital by a neighbor.
The report said the reason for the apparent suicide was not clear but quoted other reports that Kiessling left two suicide notes.
Berlin Mayor Klaus Wowereit praised Kiessling for his hard work and his "successful commitment to the World Cup," the report said.
Millions of Getty images now available for free via embed tool
Aaron Carter is still in love with Hilary Duff