One of Telegram’s most popular anonymous news channels mysteriously disappeared overnight. “VChK-OGPU” (short for “All-Russian Extraordinary Commission Joint State Political Directorate”) had more than 1.1 million subscribers before it was deleted in the early morning hours of April 7. The channel wrote extensively about Russia’s law enforcement and intelligence communities.

It’s unclear why the channel was shut down. Telegram’s press service told the outlet Mediazona that VChK-OGPU “was deleted by its owner, possibly as a result of unauthorized access,” though the channel’s founder told journalists at Dossier Center that Telegram administrators blocked the account he used to create the channel and then deleted the channel itself. The source argued that Telegram has apparently started enforcing government takedown orders, referring to the Russian authorities demanding last December that Telegram delete VChK-OGPU and several other popular channels.

Meanwhile, another source linked to VChK-OGPU told BBC Russia that there was no unauthorized access to the channel, though the SIM card used in the account that registered the channel is now apparently blocked. Another BBC source suggested that the deletion may be related to an attack on a journalist affiliated with the channel, Alexander Shvarev, whom Latvian national police summoned and warned several months ago of a possible attempt on his life by Russian intelligence.