“It’s with great sadness that we think about Kirill,” Barrie Kosky, the Komische Oper’s artistic director, said in an interview. “We’re all waiting. That’s the most frustrating and saddest thing about it.”

Mr. Kosky said that he hoped Mr. Serebrennikov would soon be able to work again at the Komische Oper and elsewhere, but that he was anxious about what the Russian director might face first. “I’m fearing that it will be a bit of Russian grotesque with shades of Bulgakov,” he said, referring to the Russian author of the satirical novel “The Master and Margarita.”

The investigation against Mr. Serebrennikov began in May 2017. Prosecutors have so far presented little to support their claims, and they have dismissed striking evidence against them — multiple newspaper reviews, for instance, of a show they say was never staged. Mr. Serebrennikov has repeatedly protested innocence, most recently on Feb. 21.

At home and abroad, the outpouring of support for the director has been enormous. A Change.org petition initiated by Thomas Ostermeier, artistic director of the Schaubühne (another Berlin theater where the Gogol Center has performed in the past) has garnered more than 50,000 signatures. Among the most prominent artists lending their support are the actress Cate Blanchett, the filmmaker Lars von Trier and the Nobel Prize-winning novelist Elfriede Jelinek.

At a news conference at the Deutsches Theater on Monday, Mr. Serebrennikov’s assistant, Anna Shalashova, urged the assembled journalists to read a campaigning website tracking the case. “You will see how Kafkaesque this whole trial is,” she said.