Two Chechens charged in the 2008 killing of Ruslan Yamadayev, a former State Duma deputy and powerful rival of Chechen President Ramzan Kadyrov, went on trial in the Moscow City Court on Wednesday.
Elimpasha Khatsuyev, 39, and Aslanbek Dadayev, 33, face up to life in prison on murder charges, which they deny. Investigators say the suspects are professional killers.
The trial, which opened with a preliminary hearing Wednesday, will reconvene July 5, the court said in a statement.
Yamadayev was killed in downtown Moscow in an apparent contract hit in September 2008, and his elder brother Sulim was gunned down in Dubai in March 2009.
A third Yamadayev brother, Isa, was attacked by his own bodyguard, Khavazhi Yusupov, in July but survived.
Yusupov has told investigators that Kadyrov personally ordered the killings of Ruslan and Sulim Yamadayev and offered $1 million to kill Isa.
Yusupov was sentenced to 8 1/2 years in prison in June. An Iranian and a Tajik were convicted in Sulim's killing and sentenced to 25 years in a Dubai prison in April, while Dubai police have accused a cousin of Kadyrov, Duma Deputy Adam Delimkhanov, of masterminding the attack.
Delimkhanov has denied involvement, and Russian prosecutors have refused to extradite him to Dubai.
Russian investigators have not named any suspected masterminds in the Yamadayev killings.