During the natural course of events, when someone dies, their body decomposes and returns to dust.
We expect this to happen every time someone dies, but on occasion, this natural decomposition does not happen the way it should.
There have been numerous instances where the body of a saintly individual has been found “incorrupt,” with limited or no sign of decomposition. In these cases nature has been suspended and the supernatural takes over.
The Catholic Church has recognized that on rare occasions certain bodies of saints have not suffered the process of decomposition. This is deemed a miraculous event and is most dramatic in cases where the saint has been buried for decades or centuries and their body remains fully intact.
St. Cecilia
St. Cecilia is often included in lists of incorrupt saints. She was a martyr who died in the 3rd century and there exists a number of legends about her life.
One such story is how her body was found incorrupt after many centuries.
Albert Kuhn narrates the story in his book, Roma: Ancient, Subterranean, and Modern Rome, in Word and Picture:
There Cecilia rested until the year 821 That was the time in which Pope Paschal removed the relics of 2300 martyrs to the basilicas in the town to safe guard them from desecration…Accordingly Paschal renewed his researches and behold! in the cavity of the wall, carefully on the outside, and only separated by partition not more than an inch in thickness from the tomb of the Prince of Apostles in the adjoining chamber, he found a coffin of cypress-wood wherein lay the body of the saint exactly as tradition described it, arrayed in a robe wrought with gold, with the wounds on her throat and at her feet the cloths with her blood. The body was incorrupt.
In 1599 the coffin was opened again when renovations were occurring in the basilica:
The cardinal raised the thin lid of the coffin and there lay St. Cecilia in the unspeakable majesty and beauty of her martyrdom, eight centuries having elapsed since Paschal gazed at her in the same manner, with the same profound veneration.
A statue placed over her tomb now represents how her body looked in 1599.
If all of these stories are true and authentic, then St. Cecilia may have been the first saint to be found incorrupt.
It is unsure if her body is still incorrupt, as it is not on display and there have been no recent attempts to exhume her body.