Factbox-A brief guide to the Catholic Church's saint-making process

VATICAN CITY (Reuters) - The Catholic Church will proclaim its first millennial saint on April 27, elevating Carlo Acutis, a teenage web developer who died from leukaemia in 2006, to the same status as Saint Francis and Mother Teresa.

Here is a brief summary of how the Roman Catholic Church recognises sainthood.

The process that can lead to sainthood, known as a "cause", cannot usually start until five years after a person's death.

In the early years of the Church, a saint could be declared such by acclamation by the people, or by cardinals, or by papal decree.

Today, the Vatican department that studies sainthood causes is known as the Dicastery for the Causes of Saints. Its origins date back to 1588, but the department has been modified several times over the years.

After the Dicastery accepts the name of a person to be considered for sainthood, that person is given the title "Servant of God".

If initial investigations show that the candidate for sainthood lived what is known as a life of "heroic virtues," that person is given the title "Venerable".

Historical and theological commissions in the Dicastery study the person's life, read his or her writings and interview people who knew the person.

At this point, in order for the procedure to continue, a miracle is needed.

Miracles are not performed by prospective saints but by God. The Church believes that, because a prospective saint is in heaven, he or she can intercede with God to perform the miracle for someone on earth who has prayed for the prospective saint's help.

A miracle is usually a medically inexplicable healing. A medical commission appointed by the Vatican determines if there was any medical explanation for the healing or not.

Miracles are not necessary if a person was a martyr, someone killed in what the Church calls "hatred of the faith".

If a miracle is determined for those who were not martyrs, the person can be "beatified" and is given the title "Blessed".

Carlo Acutis was beatified in 2020.

A second, distinct miracle must take place after the beatification in order to proceed to sainthood.

Acutis is credited with two miracles – the healing of a 4-year-old Brazilian boy with a serious pancreatic malformation and of a 21-year-old Costa Rican woman who was near death after a tragic bicycle accident.

The parents of both individuals had prayed to Acutis for help, Church authorities said.

Acutis himself was a believer in miracles. Shortly before his death, he finished developing a website to track locations of reported Catholic miracles around the world.

Other saints who died at a young age include St. Therese of Lisieux, who died at 24 in 1897 and was known for promoting a "Little Way" of love and charity; and St. Aloysius Gonzaga who died at 23 in 1591 after caring for victims of an epidemic in Rome.

(Reporting by Joshua McElwee; Editing by Andrew Heavens)