The exact origins of the Beluga whale, which turned up dead earlier this year, had long remained a mystery.
First spotted off the coast of Norway back in 2019, the inquisitive whale quickly caught the attention of marine biologists when it surfaced with a strange man-made harness attached to its body.
When a team from the Norwegian Directorate of Fisheries managed to remove the harness, they discovered that it was one typically used to mount camera equipment and had the words 'Equipment St. Petersburg' written on it.
The find prompted speculation that Hvaldimir may have been specially trained by the Russian navy as a 'spy whale' and had either escaped its enclosure or had been set loose.
Sadly, the whale was found dead in Norway's Risavika Bay earlier this year, leaving many unanswered questions about where it had come from and who had been training it.
Now, though, marine expert Dr Olga Shpak believers that she may have an answer to the mystery based on what she has learned through conversations with former colleagues in Russia.
Speaking as part of a new BBC documentary entitled Secrets of the Spy Whale, Dr Shpak believes that Hvaldimir had been trained to guard a Russian naval base but had chosen to flee once it was given access to the open ocean.
"Through the chain of vets and trainers the message came back - that they were missing a beluga called Andruha," she said. "I believe that when they started to work in open water, trusting this animal, the animal just gave up on them."
"What I've heard from the guys at the commercial dolphinarium who used to have him was that Andruha was smart, so a good choice to be trained."
"But at the same time, he was kind of like a hooligan - an active beluga - so they were not surprised that he gave up on [following] the boat and went where he wanted to."
Satellite images are thought to show a naval base in Murmansk with whale pens that could very well be the place from which Hvaldimir (aka Andruha) escaped.
It remains unclear how many other whales could still be present at the facility.