Chechnya's President Ramzan Kadyrov announced last week the assassination of Rastom Saleef one of the most extremist Islamic fighters, by elite Chechen forces.
Saleef, known by his fighting name, Abu Muslim al Shishani, belonged to an extremist Islamic movement that had called for the establishment of a "Caucasus Emirate" as the basis for the future Islamic caliphate.
Chechnya declared independence from Russia in 1991, leading to a bitter battle with Russian forces. A peace treaty was signed in 1996, but three years later, after Chechen fighters assisted neighboring Dagestan to also gain independence, Russia re-occupied the country. Almost fifteen years of fighting have followed - with thousands of Islamic fighters in the country behind a series of deadly terrorist attacks in Chechnya, Russia and other countries.
Saleef had spent the last year fighting the forces of Syrian President Bashar Al Assad with the Islamist rebels of the Al Qaeda-affiliated Jabhat al Nusra terrorist organization.
Websites associated with Islamic terrorist groups in Syria "credit" Saleef with the slaughter of 378 people - including soldiers and officers in the Syrian army as well as Assad regime loyalists - by cutting their throats with a knife.
Described as among the fiercest fighter in the ranks of the rebels, Saleef is said to have beheaded his victims after killing them, placing the head on top of the detached body to cries of "Allahu Akhbar" (Allah is great).
Last week, Human Rights Watch (HRW) accused Syrian rebel forces of war crimes against humanity for the execution of 180 Syrian civilians in the town of Latakia. Meanwhile also last week but on the other side of the conflict, Hezbollah men fighting alongside the Syrian military were filmed celebrating the brutal execution of a group of seriously wounded Syrian civilians.
The fighting in Syria has killed at least 110,000.