 Even so, he and his fellow "conspirators" were arrested on 23 April 1849 at the request of Count A. Orlov and Tsar Nicolas I, who feared a revolution like the Decembrist revolt of 1825 in Russia and the Revolutions of 1848 in Europe.The members were held in the well-defended Peter and Paul Fortress, which housed the most dangerous convicts.The case was discussed for four months by an investigative commission headed by the Tsar, with Adjutant General Ivan Nabokov, senator Prince Pavel Gagarin, Prince Vasili Dolgorukov, General Yakov Rostovtsev and General Leonty Dubelt, head of the secret police.