Vladimir Putin's daughter traveled frequently to Munich between 2017 and 2019, per a joint report.
She had a long-term relationship with a former ballet director in the city, per the report.
The report provides insight into the lives of Putin's family, which he's fought hard to keep secret.
Russian leader Vladimir Putin has long sought to shield his family and children from the public eye, shrouding their identities and whereabouts in secrecy as the West aims to sanction them.
Now, new details have emerged about the personal life of one of his two identified daughters thanks to a joint investigation published Thursday by Russian news outlet Important Stories and German news site Der Spiegel.
The outlets reported that they obtained flight records showing that Katerina Tikhonova, 35, flew more than 50 times to Munich, Germany, between 2017 and 2019.
Their findings also suggest that Tikhonova, thought to be Putin's youngest daughter, is in a serious, long-term relationship with Igor Zelensky, a 52-year-old Russian former ballet star who stepped down as Munich's state ballet director in April.
Tikhonova would travel between Moscow and Munich on chartered flights paid for by the state, and with members of Putin's presidential security service, Important Stories reported, citing flight logs and a passenger list.
The same list and several passport scans also indicated that Tikhonova and Zelensky had a daughter born in 2017 - around the same time that Tikhonova split from her former husband, Russian businessman Kirill Shamalov.
Important Stories said it obtained the passport scans through an email sent between Tikhonova's bodyguard, who booked the tickets, and Russia's presidential security agency.
The outlets did not name the couple's daughter but wrote that part of her name is Igorevna, indicating it was derived from Zelensky's first name.
The passenger list, which was for a flight on December 9, 2019, showed that Tikhonova and Zelensky landed in Moscow's Vnukovo airport with an entourage of nannies and presidential security, along with their apparent two-year-old daughter and a piano teacher, Important Stories reported.
Around this time, Tikhonova seemingly decided to move to Munich, according to a letter in her bodyguard's archives, per the outlet. According to Important Stories, an officer in Russia's presidential security services also received an email in October 2019 titled "Moving to Germany."
Der Spiegel reported that when it approached Zelensky's residential address in Munich, they found only his ex-wife, former ballet dancer Yana Serebriakova, who refused to answer their questions.
Zelensky became the artistic director of Munich's Bavarian State Ballet in 2016 but stepped down on April 4 citing private family circumstances. According to Serge Dorny, the managing director of the Bavarian State Opera, Zelensky was asked to leave for failing to condemn the war in Ukraine publicly.
The new details surrounding Tikhonova's penchant for travel to Germany may raise awkward questions for Putin, who's condemned members of the Russian elite who have remained in the West for being "scum and traitors."
Tikhonova, a former acrobatic dancer, now runs a startup incubator worth $1.7 billion at Moscow State University. In April, the US Treasury Department identified her as one of Putin's daughters as part of the West's sanctions on Russia.
Another of Putin's daughters identified by the US is Maria Vorontsova, a 37-year-old pediatric endocrinologist and genetics researcher. She is listed as a leading researcher at the Endocrinology Research Center in Moscow. Its website states that she is also the deputy chairman of the Russian Society of Young Endocrinologists.
The whereabouts of Tikhonova, Zelensky, and their purported daughter are currently unknown, Der Spiegel and Important Stories reported.