Russian-Israeli historian Artyom Kirpichenok has been subjected to brutal treatment while in Shin Bet custody, including interrogations lasting up to 24 hours, sleep deprivation, prolonged handcuffing, and threats, according to his lawyer.

Kirpichenok, 51, disappeared on August 2 shortly after arriving at Ben Gurion Airport from Yerevan. His whereabouts remained unknown for nearly three weeks before his supporters revealed that he was being held at a detention facility in Petah Tikva.

His lawyer, Inna Lebedinskaya-Katz, was finally allowed to meet with him for around an hour on Sunday after repeatedly seeking access, according to Nika Dubrovsky, a Russian-born artist and writer campaigning for his release.

Citing Lebedinskaya-Katz, Dubrovsky said Kirpichenok has faced interrogation sessions lasting 18 to 24 hours while deprived of sleep. He is allegedly being kept handcuffed and hunched over on an iron stool fixed to the floor, with three or four interrogators standing behind him “shouting, threatening, and applying constant pressure.” He has also allegedly been threatened with life imprisonment.

Kirpichenok is in “tolerable physical condition” and has no immediate health complaints, but is “exhausted, tormented and deeply depressed,” Dubrovsky wrote on X on Monday.

”He understands that his friends have not abandoned him. He is holding on and sends his greetings to everyone,” she wrote. Kirpichenok also asked that no one come to Israel.

The allegations have not been independently verified. However, international human rights groups previously documented sleep deprivation and painful restraint during Shin Bet interrogations. Israel’s Supreme Court has ruled against deliberately using prolonged sleep deprivation to break suspects.

Kirpichenok is being held underground with the lights on around the clock and denied books and writing materials, Dubrovsky cited his lawyer as saying. A gag order remains in force, and the defense has yet to receive the case files or details of the accusations.

Kirpichenok, a dual Russian-Israeli citizen and Middle East expert, is known for criticizing Israel’s policies toward Iran and Palestine. Moscow sought information from the Israeli authorities following his disappearance and said it is closely monitoring the case.

Kirpichenok recently worked with media outlets and civic organizations in Türkiye and Iran and frequently traveled to Iran. Israeli citizens are generally prohibited from traveling to countries they are at war with. Dubrovsky, however, said the trips now appear to be of little interest to investigators.

Born in Russia, Kirpichenok moved to Israel in the 1990s, studied at the Hebrew University of Jerusalem and served in the Israel Defense Forces before returning to Russia. He later became a vocal critic of the Israeli government and its military campaign in Gaza, describing Israel as a Western “colonial project” in his recent book ‘Israel: The Road to Catastrophe’.

The Israeli authorities have yet to publicly disclose any charges against him.