Rakhat Aliev, once the husband of the eldest daughter of Kazakhstan's president, has been arrested in Austria.
Aliev is wanted in Kazakhstan for allegedly kidnapping and murdering two bankers in 2007, as well as other serious charges.
Austrian police opened their own investigation into Aliev in 2011.
Aliev's lawyer, Manfred Ainedter, said on June 6 that Aliev -- who has been living in self-imposed exile in Europe -- voluntarily turned himself in to Austrian authorities in Vienna the previous evening.
He said an Austrian arrest warrant for Aliev had been issued in May that included charges "from murder to kidnapping."
Austrian authorities twice declined to extradite Aliev to Kazakhstan, citing concerns he would not receive a fair trial.
Aliev was Kazakhstan's ambassador to Austria in 2007 when the charges against him first surfaced. By that time, he had become a critic of his former father-in-law, President Nursultan Nazarbaev.
Aliev has repeatedly said the charges are politically motivated.
Based on reporting by Reuters, AFP, and Interfax