In Suzdal, Rubin was subjected to a cramped punishment cell barely bigger than a man and to the torture of solitary confinement. With his health starting to fail, Rubin was eventually compelled to give false written testimony against David Riazanov to secret police investigators. Rubin claimed that he had kept an envelope containing secret documents of the mythical "Menshevik Center" in his office at the Marx-Engels Institute before discreetly passing them along to David Riazanov. Following a show trial conducted by prosecutor Nikolai Krylenko, Rubin was found guilty of participation in the plot and sentenced to a 5-year term of imprisonment. This coerced testimony of Rubin was used in building a case against his former employer, David Riazanov.