Azerbaijan has been pushing back against Russian dominance in the Caucasus region, seeking closer ties with Turkey and Israel.

Azerbaijan's Prosecutor General has now launched a criminal case accusing Russian police of torturing and deliberately killing the brothers. A post-mortem conducted in Azerbaijan found they died from "post-traumatic" shock after being severely beaten in custody.

Deaths in custody, media offices raided, and beaten and bloodied suspects paraded in court — relations between Russia and Azerbaijan, once considered close, have sharply deteriorated in recent days amid a series of high-profile incidents.