VATICAN CITY — In the three-plus centuries since the death of Kateri Tekakwitha, Native Americans and many others often have pleaded with the Vatican to saint her.

What made it happen, according to her principal advocate at the Vatican, was a change in the rules for determining when a cure from centuries past could be judged “miraculous” and the emergency delivery of a bone fragment believed to have belonged to Kateri to a Seattle hospital in 2006, where a Lummi Indian boy was on his death bed.

The man behind the drive within the Vatican for Kateri’s canonization, the Rev. Paolo Molinari, has been marshalling the evidence for more than a half-century, carrying out a role known here in Vatican City as postulator. A Jesuit priest, Molinari was assigned the case, along with many others, by the order’s father-general. Even after his retirement — he’s now 88 — he kept the Kateri file. It was only a year ago that he completed assembling the documentation that persuaded Pope Benedict XVI to announce her canonization.

Molinari was closely involved in the inquiry that led to Kateri’s beatification in 1980 and in the change of rules for how to recognize miracles that took place before modern medicine — Kateri died at the age of 24 in 1680. In an interview, Molinari offered a rare insider’s look at the procedure for making a saint.

“I had a good relationship with Pope John Paul II,” he told McClatchy. “So I approached him,” aware the Pontiff also had a “keen interest” in Kateri Tekakwitha.

“He had asked my opinion about several theological issues concerning the causes of saints. And therefore I said to him, look, it’s understandable that the church — before giving a judgment about a miracle, an action of God that cannot have an explanation in natural science — demands that all the medical evidence be produced.

“But I said, with regard to ancient causes, what can we do? Three centuries ago, they didn’t have X-rays, they didn’t have the CAT scan, and all the rest.”