They were imprisoned in the two-story Ipatiev House, the home of the military engineer Nikolay Nikolayevich Ipatiev, which ominously became referred to as the "house of special purpose". Here the Romanovs were kept under even stricter conditions; their retinue was further reduced and their possessions were searched. Following allegations of pilfering from the royal household, Yakov Yurovsky, a former member of the Cheka secret police, was appointed to command the guard detachment, a number of whom were replaced with trusted Latvian members of the Yekaterinburg "special-service detachment". The remaining Romanovs left Tobolsk by river steamer on 20 May and arrived in Yekaterinburg three days later. By the first weeks of June, the Bolsheviks were becoming alarmed by the Revolt of the Czechoslovak Legion, whose forces were approaching the city from the east. This prompted a wave of executions and murders of those in the region who were believed to be counter-revolutionaries, including Grand Duke Michael, who was murdered in Perm on 13 June.