An amateur Russian military historian was sentenced to 12 and a half years in prison for treason this week, the latest in a string of treason and espionage convictions targeting a wide range of Russians.

Andrei Zhukov was arrested in June 2018 on suspicions linked to “the history of the Russian Armed Forces and his vigorous activity online,” according to the state-run TASS news agency.  

The Moscow City Court found Zhukov guilty on charges of high treason, TASS reported Tuesday. He will serve his time in a high-security penal colony. 

State prosecutors had requested 17 years in maximum-security penal colony for Zhukov.

The trial was closed to the public because some of its materials were classified as top secret, according to TASS.

Zhukov’s defense team vowed to appeal his “illegal and groundless” sentence, TASS reported.

The mandatory minimum sentence for high treason is 12 years and the statutory maximum is 20 years.

According to TASS, Zhukov’s colleagues said that his interests included the formation, reassignment and deployment of Russia’s military units from World War I to the present.  

Zhukov has also published books on World War II participants and their families, as well as military awards.

Russian authorities have in recent years imprisoned or charged scientists, journalists, pensioners and government officials for high treason or disclosing state secrets.