Leonid Maksimovich Kats,a 22-year-old Russian mathematician and promising young scholar, has been detained since September 2025 and held in pretrial detention on a state treason charge reportedly linked to a donation to a charity assisting Ukrainian children. The evidence against him remains unavailable to the public, as the case is being conducted behind closed doors. CCS urges authorities to ensure his due-process rights and calls for his release and the termination of the prosecution if there is no credible evidence that he posed a threat to national security.
https://memopzk.org/en/news/leonid-kats-is-a-political-prisoner
September 3, 2026
Alexander Vladimirovich Gutsan
Prosecutor General of the Russian Federation
Prosecutor General’s Office of the Russian Federation
15a Bolshaya Dmitrovka Street, Building 1
Moscow, GSP-3, 125993
Russian Federation
Dear Prosecutor General Gutsan:
The Committee of Concerned Scientists (CCS), an independent organization of scientists, physicians, engineers, and scholars dedicated to protecting the human rights and academic freedom of our colleagues throughout the world, writes to express its profound concern regarding the continuing detention of Leonid Maksimovich Kats, a 22-year-old Russian mathematician and recent graduate of the Faculty of Mathematics of the National Research University Higher School of Economics.
Mr. Kats is an exceptionally promising young mathematician. Following completion of his bachelor’s degree in 2025, he reportedly received offers for further study from several highly regarded institutions, including the Moscow Institute of Physics and Technology, Skoltech, École Normale Supérieure, and Université Paris-Saclay. He was preparing to continue his graduate education in France when he was detained.
According to publicly available information, Mr. Kats was taken into custody on or about September 30, 2025. During the following two months, he was subjected to four consecutive administrative detentions of approximately fifteen days each. On December 2, 2025, the Meshchansky District Court of Moscow ordered his pretrial detention under Article 275 of the Criminal Code of the Russian Federation on a charge of state treason.
Independent Russian sources report that the accusation concerns a financial contribution to a charitable organization assisting Ukrainian children. Because the criminal proceedings are closed, neither the evidence supporting the charge nor the precise factual basis for characterizing the alleged contribution as state treason has been made public.
Mr. Kats has now been deprived of his liberty for nearly eleven months. Publicly available information continues to describe his criminal case as being at the investigative stage, and we are unaware of any public trial date. He is reported to remain in custody at SIZO-3 in Moscow.
CCS recognizes the responsibility of every state to investigate conduct that it reasonably believes threatens its national security. At the same time, allegations of state treason — carrying exceptionally severe potential punishment — require especially rigorous adherence to due process, reliable evidence, access to independent counsel, protection from coercion, and respect for the fundamental rights of the accused.
We respectfully ask your Office, within the scope of its supervisory authority, to:
- Review the legal and evidentiary basis for Mr. Kats’s continued pretrial detention and prosecution, including whether the conduct alleged against him can lawfully constitute state treason under Article 275;
- Ensure Mr. Kats’s full and confidential access to independent legal counsel and appropriate contact with his family;
- Ensure that his conditions of detention at SIZO-3 comply with Russian law and applicable international standards;
- Provide Mr. Kats and his counsel with all procedural protections required by law and permit the greatest degree of transparency compatible with legitimate protection of classified information; and
- Consider his release from pretrial detention and, if the reported humanitarian nature of the alleged financial contribution is accurate and there is no evidence that Mr. Kats intended to harm the security of the Russian Federation, take appropriate steps toward termination of the prosecution and restoration of his freedom.
Mr. Kats was at the beginning of a promising international scientific career when his education was interrupted by his detention. The scientific community has a particular interest in ensuring that young scholars are not deprived of their freedom and careers without compelling evidence, fair procedures, and scrupulous respect for their fundamental rights.
We therefore respectfully request your urgent attention to Mr. Kats’s case and would be grateful to receive information regarding his present legal status, health and conditions of detention, consistent with applicable Russian law.
Thank you for your consideration. We hope that the Russian authorities will take all appropriate steps to safeguard Mr. Kats’s rights and permit him to resume his mathematical studies and scientific career.
Respectfully yours,
Joel L. Lebowitz, Walter Reich, Eugene M. Chudnovsky, Alexander Greer
Co-Chairs, Committee of Concerned Scientists
Cc:
Yana Valeryevna Lantratova
Commissioner for Human Rights in the Russian Federation
19 Smolensky Boulevard, Building 2
Moscow 119121
Russian Federation
Email: doc@rightsrf.ru
His Excellency Alexander Nikitich Darchiev
Ambassador of the Russian Federation to the United States
Embassy of the Russian Federation
2650 Wisconsin Avenue, N.W.
Washington, DC 20007
USA
Email: rusembusa@mid.ru