For consideration for sainthood, a person must be dead for at least five years and must have led a holy life. Previously, two post-mortem miracles were required for sainthood, but the pope can waive this requirement.
A diocesan tribunal is the first step in nominating a person for canonization. The tribunal investigates the deceased person’s life and attempts to find proof of righteousness. The tribunal calls witnesses to verify that claims of the person’s piousness are accurate. If the person was involved in any sinful behavior, there must be proof of repentance to move the application for sainthood forward.
After completing the initial investigation, the tribunal forwards all necessary documents to the Vatican. A group of nine theologians judge whether or not the application is worthy of being passed onto the Vatican bishops and cardinals. If the theologians decide the application is acceptable, they give the application to the bishops and cardinals for their approval, who then pass it on to the pope for final consideration.
Previously, requirements for canonization stipulated all would-be saints to have performed two post-mortem miracles; however, the pope has the authority to waive this requirement. Pope Francis dispensed with the qualification in 2014, to canonize Pope John XXIII. Pope John XXIII had been a candidate for sainthood for decades but lacked a second post-mortem miracle.