Ambassador Andrei Karlov’s body was sent home to Moscow Tuesday, his widow bowed over with grief.

It was another act of violence sparked by the Syrian civil war.

Karlov was killed Monday by Mevlut Mert Altintas, a 22 year-old Turkish police officer, apparently in revenge for Russia’s deadly intervention in the Syrian civil war.

“Whoever has been part of this cruelty will pay for it one by one,” the gunman shouted.

Six of Altintas’ family members and his roommate have now been detained as the Turkish authorities investigate.

The assassination follows a string of deadly bombings in Turkey, many connected with the Syrian conflict.

Moscow’s airstrikes have helped the Syrian regime win back the city of Aleppo but the cost has been counted in Syrian lives; Tens of thousands have been forced to flee.

Russia and Turkey are on opposite sides in the Syrian civil war but recently relations have improved. The two countries negotiated a ceasefire last week to help evacuate Syrian civilians.

But even a warming between Turkey and Russia won’t stop Syria’s bloodshed from spilling over its borders.