(CNN) Two guinea pigs and a cat belonging to former Russian spy Sergei Skripal, poisoned in a nerve agent attack in the UK last month, have died, British authorities have said.

The two guinea pigs were found dead in Skripal's house some time after the attack, apparently from dehydration, and a cat was put down after being discovered in a "distressed" state. Police sealed the house after Skripal and his daughter Yulia were discovered unconscious on a bench in Salisbury on March 4.

"When a vet was able to access the property, two guinea pigs had sadly died," the UK Department for Environment, Food and Rural Affairs (DEFRA) said in a statement. "A cat was also found in a distressed state and a decision was taken by a veterinary surgeon to euthanise the animal to alleviate its suffering."

The guinea pigs "most likely... died due to a lack of water," a DEFRA spokesperosn told CNN later.

The deaths are the latest peculiar developments in a story that has taken a turn for the absurd in recent days. Apparently in an effort to shift the debate away from the issue of culpability, a succession of Russian officials have attempted to make light of the whole affair.