ANKARA, Turkey — In a string of assassinations reminiscent of spy thrillers, six Chechen exiles were gunned down in Istanbul in 2008-11. The murders, blamed on Russian secret agents, were almost forgotten last year until a Turkish-born Chechen, a vocal advocate of Chechen independence and an influential figure in Turkey’s ethnic Caucasian community, was killed in his office in downtown Ankara. The suspicion quickly focused on Russia again.

But in a surprise twist more than a year later, the victim’s family and lawyer have asked the prosecution to follow a new line of inquiry: Medet Onlu, they suspect, was killed because he was an obstacle on the “jihadist highway” to Syria, opposed to Chechen rebels exiled in Turkey joining the war. They claim a systematic effort is underway to cover up the murder.

“Onlu’s stand against the exploitation of Chechens in Syria was very important. … In the Caucasian community [in Turkey], he was a person in a leadership position who took the risk of taking a stand against this,” lawyer Erdal Dogan told Al-Monitor by telephone. “We have serious suspicions that people in public office … made way for the murder and we believe they are still impeding the capture of the suspects.”

Chechen fighters — some battle-hardened, others wannabes — figure prominently in jihadist ranks in Syria, often credited as fierce combatants and military strategists. As Al-Monitor’s Vitaly Naumkin writes: “They didn’t come to Syria from Russia … but from Georgia, Turkey and European countries that once provided them refuge as freedom fighters.”