Two security officers in charge of the investigation have now been removed from the case and are themselves under investigation for misconduct amid a rolling purge of Uzbekistan’s once-untouchable security service.

The twists and turns in Mr. Abdullaev’s case point to what, 18 months after the death of Uzbekistan’s longtime dictator, Islam Karimov, is the central question hanging over efforts by new leadership to open up one of the world’s most repressive countries: Can a brutal and once all-powerful security apparatus with roots deep in the former Soviet republic be transformed into a law enforcement agency?

Mr. Abdullaev, along with many other government critics, is still under arrest. He told his lawyer, Sergei Mayorov, that after his arrest he was beaten repeatedly and then kept naked for six days in a freezing cell without sleep. He said he was given food only on the fifth day of his detention, and even then only after he had collapsed. Officials warned him that unless he confessed his wife and daughter would be raped, his lawyer said.

The internet is still censored, albeit less than before, and fear of the security service, known by its Russian-language acronym, S.N.B., remains widespread. It is still considered dangerous even to utter the name of the security service in public.