Rusik's skill at sniffing out hidden fish was so good that he had replaced the local sniffer dog.
The cat detective walked into a police station a year ago as a stray kitten. The staff quickly adopted him, feeding him on scraps of fish confiscated from smugglers.
Most of the world's caviar comes from the Caspian Sea.
And because there's so much money to be made, the sturgeon has been hunted to the brink of extinction.