Medics were unable to save Vitaly Likhanov, 41, and Sergey Fundament, 47, who served in the SOBR special forces of the national guard.
They fell as they dropped from a hovering Mi-8 helicopter onto the deck of a ship in Arctic city Murmansk, northwestern Russia.
Military investigators are now checking whether a blunder in bad weather led to their ropes being too short for the height of their descent.
Another theory is that the ropes had been damaged causing the death plunges.
A criminal probe into possible criminal negligence has been launched by the Investigative Committee of Russia’s Northern Fleet.
The possible punishment for such offences is up to seven years in prison.
President Vladimir Putin expressed “deep condolences” over the tragedy.
But Olga Funadament, widow of one of the dead officers, said “any previous complex landing was always without any mistakes”.
Her husband, with whom she had three children, had two awards for “courage” in “services to the fatherland”.
Last month, Daily Mirror exclusively told how Russia is launching a deadly new “underwater sabotage sub” capable of diving almost two miles and destroying communications cables.
Up to £8trillion worth of key financial transactions and other data passes daily through the world’s 380 seabed “comms lines,” all of them vulnerable to attack.
Moscow’s naval intelligence spies have been suspected of trying to interfere with the west’s cables for months in a “dirty war” bid to disrupt our economies.
Sources claim a deep-sea version of Russia’s AS -15 Kashalot sub will be launched by a bigger craft called the Belgorod for sea trials.