The forensic report has proved that the bodies were beheaded through a sharp edged weapon . You cant surgically behead by firing 30 rounds from Ak-47 .The bullet wounds are different from knife wounds.
The operation was done by soldiers 29 baloch regiment of pakistan army . Would like to mention that Balochs are basically tribal people and belong to a region where beheading is not uncommon. Also , if you see previous news , beheading of captured POWs is a regular act in Pakistan . Though i admit that mostly Taliban does it.
Having heard this , dont assume that Taliban came to Indian side and did this act . Even if they did, they must be having active support of Pakistani army and did all this activity under full knowledge of Pakistan army.