Who is Ryzhik from The Case of Comrade Tulayev and what is their importance?

Ryzhik is a deportee sent to the outer regions. His past is filled with prisons and deportations, and the authorities involved in the Tulayev case decide that he is the perfect old Trotskyist to add to the dossier of the case, even though he was nowhere near Moscow when Tulayev was killed. Ryzhik knows he will be executed, so he goes on a hunger strike and dies in prison before they are able to question him further.