Two Kazakhs are expected to appear in court in Austria on April 14 over the killing of two bankers.
Former intelligence chief Alnur Musaev and ex-presidential bodyguard Vadim Koshlyak are accused of aiding the abduction and murder of two managers of Kazakhstan’s Nurbank in 2007.
The main suspect, Rakhat Aliev, was found hanged in a Vienna prison in February.
Aliev, former son-in-law of President Nursultan Nazarbaev, was sacked from his post as Kazakhstan's ambassador to Austria and sentenced in absentia to 40 years in prison for organized crime and an attempted coup.
He denounced the case against him as politically motivated.
Austria refused extradition requests by Astana and began its own investigations.
In June 2014, Aliev turned himself in to Austrian authorities, who charged him with killing the Kazakh bankers.