Israilov, a former rebel fighter, had been detained by the Russian security forces in Chechnya, but was amnestied and became a bodyguard for the pro-Moscow leader.
He ultimately fled to Europe where he filed a lawsuit against Russia, accusing Kadyrov of abductions and torture. He claimed that Kadyrov had personally tortured him with electric shocks.
Kadyrov's critics have been targeted on previous occasions, a reflection of the volatile web of rivalries in Chechnya.
In November 2006, the former head of one of Chechnya's shadowy security forces, Movladi Baisarov, was shot dead by Chechen security officers in Moscow.
Two years later, Ruslan Yamadayev, a former Russian lawmaker widely believed to be the brains of the opposition to Kadyrov in Chechnya, was assassinated in a drive-by attack as he stopped at a traffic light just outside the British Embassy in Moscow.
-- Aslan Doukaev