Russian prosecutors on Tuesday opened a criminal investigation into how seven sailors were trapped under water inside a mini-submarine for three days.
An initial investigation has uncovered evidence of negligence by officials, said a statement from Pacific Fleet military prosecutors.
"The investigation has been launched after initial checks by prosecutors showed that some officials violated regulations while preparing the submersible for the mission and during the mission," said the statement.
One of the crew members who had been on the AS-28 mini-sub said Tuesday that the vessel had been sent into the Pacific Ocean to investigate an underwater surveillance antenna that had become entangled in fishing nets, reports CBC News.
According to Mosnews, the Russian craft was trapped 190 meters beneath the surface for three days after becoming caught on a fishing line.
The UK team’s Scorpio robot cut the vessel free as the seven crew on board faced running out of oxygen within hours.
Speaking at Glasgow’s Prestwick Airport, Commander Riches said some of the rescuers had been overcome by emotion when the sub finally rose to the surface.
“At that moment when the rescue vehicle arrived on the surface, I can’t ever explain to you properly the feeling of elation,” he said.
“It would be wrong of me to say grown men don’t cry - a lot of grown men were crying that day.”
Armed Forces Minister Adam Ingrams paid tribute to the Royal Navy and RAF teams involved in the operation.
He said: “This was down to the qualities of the crew that went down to rescue them.
“There was a world focus on them. And what they did was truly magnificent.”