The suspect, Sergei Seredenko, 57, was detained early on this month, on the direction of the prosecutor's office and by the Internal Security Service (ISS), ERR Russian says (link in Russian).

Seredenko has in the past participated in events organized by "Immortal Regiment" (Russian: Bessmertniy Polk – a civic society which marks May 9, "Victory Day" (in World War Two), annually across Russia and other countries with large Russian minorities). He is also a member of the United Left Party (Ühendatud Vasakpartei), a non-parliamentary, very small political party predominantly representing the Russian-speaking populace, ERR Russian reports.

Seredenko's employer was, according to ERR Russian, Maardu High School (Gümnaasium), just east of Tallinn, where he worked as a janitor. While a person of that name and role is listed on the school's website, Delfi says that Seredenko works as a lawyer (link in Estonian), though also cites his employment as a janitor at the Maardu school.

The Delfi piece also says that in 2019 he had been involved in finding people willing to appear in an anti-NATO television broadcast being filmed by a Russian channel in the eastern Estonian town of Narva.

Seredenko is under suspicion of acting against Estonia, suspicions which the prosecutor's office feels are reasonable.

The news comes soon after an Estonian citizen and noted marine scientist, Tarmo Kõuts, was sentenced to three years in prison after being found guilty of spying on behalf of the People's Republic of China. Another woman suspect in that case is still in detention, awaiting judgment.

Seredenko is, according to Delfi, an Estonian citizen.

Seredenko is, the prosecutor's office says, charged under Article 235 of the Penal Code, which refers to maintaining a relationship with a foreign state, a foreign organization or a person acting on behalf of a foreign state and which may be punishable by up to six years' imprisonment for the purpose of committing an offense.

Seredenko's defense lawyer Vladimir Sadekov declined to comment when approached by ERR, merely saying that he hoped his client's health was good given his age.

Another lawyer contacted by ERR Russia, Mstilav Rusakov wondered how a janitor might have access to state secrets.

Follow ERR News on Facebook and Twitter and never miss an update!