Estonian authorities believe that Vyacheslav Morozov, who is now in custody in Tallinn, shared information with the Russian intelligence services. The head of the Security Police, Margo Palloson, told Estonia’s ERR public broadcaster that Morozov travelled to Russia “with a certain regularity” and cautioned Estonians to consider their need to do so in the future very carefully due to “a serious risk of coming under pressure from the Russian security services”.

Further details of the case have not yet been disclosed, though Palloson stressed that the investigation would find out exactly what information Morozov had access to and what he allegedly passed on to the Russian intelligence services.

Kristijna Tõnisson, who heads the Johan Skytte Institute of Politics and Law, where Morozov worked, told Novaya Gazeta Europe that the professor’s employment contract had been terminated at his own request on 11 January.

Until his sudden resignation, the university had no reason to suspect Morozov’s involvement in anti-Estonian activities, Tõnisson said, adding that news of the investigation came as a “shock” to everyone.

Students and staff were informed about the investigation shortly after Morozov’s departure.

“We have no further information about his arrest other than what we have been told by the Estonian Internal Security Service. We just know that it concerns espionage and gathering information for the Russian special services," Tõnisson added.

Some Russian academics have voiced their support for Morozov and cast doubt on the accuracy of the charges.

Dmitry Dubrovsky, a former associate professor at Moscow’s Higher School of Economics, said he was convinced that Morozov “would not have done anything like this willingly”.

"There could have been some kind of provocation, some kind of blackmail” by the Russian security services, Dubrovsky suggested in a conversation with independent Russian media outlet IStories, stressing that while Morozov’s wife lived in Estonia, Morozov himself regularly returned to Russia to visit his parents.

"He has always been critical of Putin’s regime and was, let’s say, in intellectual opposition — he was never a politician, but he always tried to foster greater critical and independent thought among Russians,” Dubrovsky recalled.

St. Petersburg historian Ivan Kurilla and a friend of Morozov “for over a quarter of a century” said that he considered Morozov’s arrest to be persecution on the grounds of his citizenship.

Both academics believe Morozov’s putative resignation to have been a dismissal in all but name. “It’s a bit strange to sack a person immediately, without waiting for a trial or even a formal indictment,” Dubrovsky said, calling his treatment “harsh.”

Kirill Titaev, a sociologist at Yale University, who said he didn’t know Morozov personally but knew him from his publications, told Novaya Gazeta Europe that he believed the professor’s arrest was likely to have been a mistake on the part of the Estonian security services.

“There are two fundamental questions about the arrest of Professor Morozov. First: Could such a person really start working for the Russian security services? This seems rather strange, because his entire academic biography shows us that this is a man who has published works that are far removed from contemporary Russian ideology. Not in subject matter, but in beliefs and positions. To write a dozen well-cited works that directly contradict contemporary Russian ideology, and at the same time to cooperate with the Russian security services looks a little strange. But it is, in general, imaginable,” Titaev said.

Titaev doubted the potential value that Morozov could be to the Russian security services, as there are no significant NATO forces stationed near Tartu. Besides, the Russian security apparatus tends to recruit either pro-Russian activists or those considered politically neutral, as it has a much harder time cooperating with ideological opponents, Titaev pointed out.

“Recruiting somebody whose work fundamentally contradicts the entire value system of the Russian security services is extremely difficult to imagine, if not impossible for them in their logic. This is ultimately a story about the inability to talk to an ideological opponent,” Titaev concluded.