'We tried an experiment - would a wild tiger live and produce offspring in captivity? It didn't work out, so let her live free,' an official at Russia's Tiger Special Inspection (RTSI) project told the news agency Interfax.
Hunters had been searching for the animal, a healthy 2-year-old Siberian female named Roshkosh (Luxury), since Tuesday after she broke a cage lock with a blow from her paw and escaped into a forested region of Russia's Far Eastern Primorie district.
A transponder in a collar worn by the tiger allowed trackers to find the animal's trail almost immediately, but bait in tiger traps set nearby was left untouched.
The tiger was last seen heading northward into uninhabited taiga forest.
Animal protection agency workers captured and transported the tiger to the RTSI center in July after villagers in Russia's Khabarovsk territory, some 650 kilometers to the north of Primorie district, complained of disappearing guard dogs and livestock.
Russia's rugged Far East is home to the world's largest wild population of the highly endangered Siberian Tiger. Some 350 big cats are thought to be living in the region, most in the Primorie district's Sikhote-Alin Nature Reserve.
The RTSI center is a government-funded facility for the study and protection of tigers living in Sikhote-Alin area and neighboring regions.
Russian Prime Minister Putin has been a high-profile patron of the center, and images of Putin shooting a tranquilizer dart into an adult feline have featured in his election campaigns.