A not-too-reliable source quotes BBC monitoring service as saying,

"A video recording sent to the press service of the president of the Chechen Republic of Ichkeria, Abdul-Khalim Sadulayev, says that the Armenian passenger plane of the ArmAvia air company, which crashed near Sochi on 3 May, was actually shot down by Russian air defence systems. Sadulayev said: 'We have information that the Armenian plane was shot down by the Russian authorities when the link with the plane was lost. They thought that someone had hijacked the plane and that there were mojahedin on board.' "

This is the only place that I found the info in English. I hope journalists in Armenia pay attention to this.