Although the details of who exactly ordered the execution and when are incredibly murky and clouded by various politicized accusations, the decision to execute the imperial family in Yekaterinburg was very heavily predicated on a number of exigent factors. This highly fluid context added a further layer of complexity to both the narrative and responsibility for the executions.
The overwhelming impulse for the Bolshevik leadership was to have Nicholas II tried in Moscow for crimes. Trotsky's diary entries in the thirties recalled that he and Lenin were in agreement that Nicholas II and his family should be remanded to Moscow and Trotsky would be the lead prosecutor for a media trial of the monarch and the former regime. As he wrote in his diary in the 1930s, :
a public trial which should lay open the entire reign (the policy towards peasants and workers, national and cultural policy, two wars and so on); the progress of the trial should be broadcast on the radio (?) throughout the country; reports of the trial should be read out daily with commentaries in all the volosts.
Of course, the exiled Trotsky naturally portrayed himself as in sync with Lenin on this and many other matters. Some evidence such as does suggest that Lenin was more leery of a trial and felt that while Nicholas II. Peter Voikov, one of the Ural commissars that arranged for the execution, later recalled that Lenin and the Presidium in Moscow did not want a wholesale slaughter and instead hoped to use the royal family, minus its head, as a bargaining chip with the West. But aside from the politics inside the Presidium, there was also a significant pressure from below to put Nicholas II to task for his alleged crimes. There were a number of petitions generated by the Petrograd Soviet calling for "Nicholas the Bloody" to be put on trial and this Soviet was responsible for pressuring the Provisional Government in March 1917 from allowing the tsar to leave for Britain. Letting the tsar and his family flee in exile to Britain or another Allied country was off the table for the Bolsheviks after the November Revolution as much of their constituency on the left wanted to see Nicholas II pay for events like Bloody Sunday of 1905, the activities of the Black Hundred ultranationalists, and his responsibility for Russia's entry into the First World War.
The problem for any advocate of a trial and mediated exile of the royal family was there simply was no way to safely return the Romanovs to Moscow from Yekaterinburg. The Provisional Government's earlier decision to remove Nicholas II from the capital into the Urals was intended to make such an imperial return to these urban power centers a difficult undertaking. The emerging civil war made things even worse. Yekaterinburg was in between both Omsk, where a provisional government of various White forces (Kadets, SRs and monarchists) and Samara where the White-allied Czech Legion was operating in 1918. The fear that animated the Romanovs' captors was that any member of the imperial family could be used as a rallying figure for the Whites. Although Moscow had held out hope for the possibility of a trail as late as July, the fear was that White forces would take the decision out of their hands. The advance of the Czech Legion threatened to liberate the imperial family for the Whites. Even though the neither the Whites nor the Czech Legion knew much about what lie in Yekaterinburg, this was a chance the local Bolsheviks could not take.
Whether or not Moscow directly ordered the execution or if the chain of command extended to Lenin himself, or was the decision of the Ural Regional Soviet is still unclear. While the existing evidence lends credence to the thesis that the Ural Regional Soviet likely ordered the execution on its own initiative, Moscow did sanction the executions after the fact. It is telling though that the first Bolshevik official pronouncements of the execution justified the execution on the basis of advancing Czechoslovak forces and lied by saying only the tsar was executed while his "wife and son have been sent to a secure place." This helped fuel the myth that some of the royal family escaped.
The highly contingent nature of the executions reinforced Moscow's constant hedging on the scope and responsibility of the executions. Obviously, the death of the imperial family caused a short-term PR problem for the nascent Bolshevik state. Voikov recalled that a number of his colleagues took the French Revolution as an example where the execution of Marie Antoinette and the disappearance of the Dauphin unified counter-revolutionary opinion. Trotsky's diary entries on the subject- which were always meant for posterity- likewise went to some length to justify the elimination of the imperial family as necessary due to the civil war. The highly fragmentary chain of evidence of Lenin's opinion on the matter shows that he was worried that a mass execution would be counterproductive for global opinion.
But there was a domestic component to obfuscating the executions as well. Chastising the Urals Soviet for the execution would have sent a signal within the country that Moscow's power was not as complete and more divided than the picture painted by Red propaganda. Thus it became imperative to portray Bolshevik actions as united front and downplay any potential sources of discord. There was a psychological component to the minimization of the importance of the executions. Within the Bolsheviks' own self-styling as revolutionaries, they looked to the French Revolution as paradigmatic model of how revolutionaries should act when in power. But the inability for the Bolsheviks to stage a trial for Nicholas II like the Jacobins showed that the Bolsheviks were wanting compared to their revolutionary forebears. Such an image was not in the interests of Lenin and company given the very fragile and fluctuating nature of their support.
Arguably more important than the example of the French Revolution for obfuscating the details of the executions was the Bolsheviks' own understanding of their White enemies. Often mixing stereotypes with experience, the Bolsheviks believed that the Whites placed great stock on Orthodox cultures of iconography and relics. This was why not only did the Ural Soviet take care to not publicize the location of the graves, they did not take photographs of the imperial family's corpses to prove they really were dead.
The overarching calculus in the collective actions of the Bolsheviks over the imperial family was that if they could not remain under Bolshevik control, they would need to be liquidated. While some conservative commentators like Pipes or Figes hold that the secrecy around the executions was a sign of a guilty conscience, such criticisms go too far. Once it became clear that a show trial was impossible, then it was in the Bolsheviks' interests to cut the Gordian knot and do everything in their power to ensure that the imperial family's end was only a footnote to the revolution and civil war. Terse proclamations of the death of "Nicholas the Bloody" fit within the Bolsheviks' attempts to monopolize the narrative of the revolution and its aftermath. Since a detailed account of the executions did not serve the immediate interests of fighting the civil war, the Bolsheviks saw no need to publicize them. Ironically, this very secrecy helped create a legend around the imperial family's deaths that the Bolsheviks sought to avoid.
Sources
Slater, Wendy. The Many Deaths of Tsar Nicholas II: Relics, Remains and the Romanovs. London: Routledge, 2008.
Steinberg, Mark D., and Vladimir M. Khrustalèˆv. The Fall of the Romanovs: Political Dreams and Personal Struggles in a Time of Revolution. New Haven, CT: Yale University Press, 1995.