Question: What step must precede the canonization of a Saint?
Answer: There are multiple steps to being declared a saint.
The first step is for the local bishop to open an investigation of the individual for sainthood. At this point the person is declared "Servant of God".
The second step calls for further investigation of the life of the individual by a tribunal. If all goes well, the pope declares the individual "Venerable".
The third step requires identification of a miracle attributed to the individual's intercession. After verification, the pope beatifies the individual who then is "Blessed".
The final step requires another miracle attributed to the individual's intercession. Once verified, the individual is canonized as an official Saint.