The owner of the zoo had been aware of the smugglers, and he also purchased the mother tiger.
There was a catch. The zookeeper actually got the go-ahead to buy the tiger to add to his zoo. The zookeeper could only get her once she had cubs. He was blown away when he heard that the sanctuary had found three tiger babies.
He realized that these were the cubs of the mother tiger, which he had acquired through a shady transaction.