Leonid Kats is a political prisoner
A mathematician has been charged with treason for donating to a Ukrainian charity
The ‘Political Prisoners. Memorial’ human rights project, in accordance with international standards, considers Leonid Kats a political prisoner. Kats is being prosecuted on a charge of treason for money transfers he allegedly made to a charity that helps Ukrainian children. Leonid Kats’ prosecution violates his right to a fair trial. We demand that Leonid Kats be released, that all criminal charges against him be dropped, and that his allegations of torture be investigated.
What are the charges against Leonid Kats?
22-year-old Leonid Kats is a graduate of the Faculty of Mathematics at the Higher School of Economics in Moscow. After completing his bachelor’s degree, Kats obtained offers for places on several master’s programmes at leading universities in Russia and France, including the Moscow Institute of Physics and Technology, the Skolkovsky Institute of Science and Technology, the École Normale and the University of Paris-Saclay. As well as science, Kats was also interested in politics. In February 2021, he was detained at a protest rally in support of Aleksei Navalny.
On 30 September 2025, Leonid Kats was to fly to France to continue his studies. However, before he reached the airport, he was detained in the street by unidentified men in plain clothes. His relatives were only informed of his detention the following day.
Leonid Kats was then jailed for four consecutive 15-day jail terms on charges of petty hooliganism and disobeying the police. According to the security forces, Kats allegedly swore and harassed passers-by immediately after each arrest.
According to the publication T-Invariant, in the first 24 hours of his detention, Leonid was interrogated using electric shocks and other forms of physical coercion, after which he signed blank sheets of paper. This occurred before a criminal case had been opened against him, when he had neither procedural status nor access to a lawyer.
On 2 December 2025, Leonid Kats was remanded in custody on a charge of treason (Article 275 of the Criminal Code of the Russian Federation). According to media reports, the charge was based on donations Kats had allegedly made to a Ukrainian charity.
Why do we consider Leonid Kats a political prisoner?
The charge of treason against Leonid Kats is unfounded. Neither humanitarian aid to the civilian population of Ukraine nor support for the Ukrainian army in repelling aggression can be regarded as activities ‘against the security of the Russian Federation.’ Treason charges of this kind are frequently used to prosecute dissidents and intimidate society.
Leonid Kats was tortured to force him to make a confession. Furthermore, he was held for two months in jail on a series of trumped-up administrative-law charges. Deprivation of liberty prior to the initiation of criminal proceedings also indicates that the criminal prosecution was itself unlawful. It is clear the investigators needed time to fabricate a case against Kats given the weakness of the evidence.
Leonid Kats’ case is being heard in camera; the case materials, and even information about the hearings, are withheld from the public.
A detailed description of Leonid Kats’ case and of our position is available on our website.
How can you help?
You can write to Leonid Kats at the following address:
RU:
Российская Федерация, 123308, г. Москва, 1-й Силикатный проезд, д. 11, корп. 1, ФКУ СИЗО-3 ГУФСИН России по г. Москве, Кац Леонид Максимович, 2003 г. р.
EN:
Leonid Maksimovich Kats (born 2003), Remand Prison No. 3, Federal Penitentiary Service of Russia for the city of Moscow, 11 (building 1), 1st Silikatny Proezd, Moscow, 123308, Russia.
You can also send emails via F-Pismo (for payment with Russian bank cards), ZT (for payment with all bank cards), and Memorial-France (free of charge).
Please note that letters in languages other than Russian are highly unlikely to reach the intended recipient.
You can donate to help all political prisoners in Russia.
