The court said a swift verdict is not planned but public broadcasters ZDF said that Keller would make a statement on his future within the next days after a no confidence vote on Sunday from presidents of Germany’s regional football bodies.

“A decision is expected in May, but not this week or next week,” sports court head Hans E Lorenz told dpa, adding that proceedings would take place behind closed doors.

Keller compared Koch, who is a judge outside, to Nazi judge Roland Freisler. Further details of the comparison are not known.

Keller has addressed his staff in an emotional letter but so far insisted he won’t resign.

Freisler attended the Wannsee Conference, which set in motion the Holocaust. Later, he was appointed president of the People’s Court, where he handed down around 2,600 death sentences from 1942 to 1945.

General secretary Freidrich Curtius also got a no confidence vote on Sunday while Koch and treasurer Stephan Osnabruegge meanwhile won votes of confidence.

The DFB has been bogged down in a long-standing power struggle between Keller and Curtius who called the ethics committee to look into the Nazi analogy.

Curtius, who is also investigated by the sports court in two cases first handled by the ethics committee, has said he would be prepared to stand down.

Osnabruegge has also reportedly said he would not seek re-election next year.