A man who was detained in Russia’s republic of Bashkortostan amid a region-wide crackdown on protesters and activists has died in police custody, the human rights group Za Prava Cheloveka (ZPC) reported Friday, citing the man's sister.

Law enforcement officers detained Rifat Dautov following a protest last Friday in Bashkortostan's capital of Ufa, his sister, identified only as Zaliya, told ZPC. While the exact circumstances of the man's detention remain unclear, his sister said that he did not take part in the protest last week and was simply walking in the area at the time, adding that he had allegedly received a “written warning” from police.Zaliya said an official in the village where her parents live “received a call [from] forensic examiners in Ufa, saying that they couldn't find relatives to identify [the body].”According to the sister, authorities said Dautov died from a heart attack induced by heavy intoxication, but relatives have not yet been allowed to visit the morgue where Dautov’s body is said to be held. The Moscow Times could not independently verify ZPC's report and it was unclear on what grounds Dautov was detained by police. Last week, Bashkortostan witnessed some of the largest protests in Russia since the invasion of Ukraine as thousands gathered in the Ural Mountains region to support jailed Bashkir activist Fayil Alsynov.At one of the protests, police were filmed beating demonstrators with truncheons and using tear gas and smoke grenades to disperse crowds.So far, authorities have opened at least 123 administrative and 16 criminal cases in connection to the demonstrations, according to the independent human rights watchdog OVD-Info.One of Alsynov's supporters, 42-year-old Dim Davletkildin, was hospitalized in critical condition on Friday after being beaten by security forces while in detention. “Medical records confirm that he was subjected to violent beatings by security forces and was forced to testify under pressure,” a group of Davletkildin's friends and relatives wrote on Telegram, citing copies of his medical records. Davletkildin was found to have a spinal fracture and anemia, OVD-Info said, citing the man’s relatives.