The daughter of a close ally of Russian President Vladimir Putin was killed near Moscow.
The Russian Investigative Committee said Daria Dugin died after her car exploded on her way home.
It is believed that her father, Russian philosopher Alexander Dugin, known as "Putin's brain", may have been the intended target.
Dugin is a prominent ultra-nationalist ideologue who is believed to be close to the Russian president.
Alexander Dugin and his daughter were guests of honor at a festival near Moscow, where the philosopher gave a lecture.
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Described as a family event for art lovers, The Tradition takes place in the Zakharovo resort, where Russian poet Alexander Pushkin once stayed.
According to the Russian media platform "112", the father and daughter were scheduled to return from Saturday evening's event in the same car, before Dugin made a last-minute decision to move separately from his daughter.
Unverified footage published on Telegram shows Dugin watching what is happening in a state of shock, while emergency services arrive at the scene of the burning car wreck.
The BBC was unable to independently verify the footage.
Investigators confirmed that Daria Dugin died at the scene near the Polish village of Vyazyme.
They added that an explosive device detonated before the car caught fire. Forensic and explosives experts are investigating the accident.
Although he does not hold an official position in the government, Dugin is a close ally of the Russian president, and has been described as "Rasputin Putin".
The philosopher's daughter, Daria Dugin, was in turn a prominent journalist and commentator who supported the Russian invasion of Ukraine.
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Earlier this year, the UK authorities accused the 29-year-old of contributing to the practice of "disinformation" on the Internet in connection with the Russian invasion of Ukraine.