Gueranger’s Life of St. Cecilia, translated from French into English, includes a translation of an eyewitness account by the historian, Cardinal Baronius.
This is super-awesome.
A lot of descriptions of the St. Cecilia statue say, “Well, obviously the sculptor was lying when he said he sculpted it just as he saw it,” or “Well, obviously somebody mucked around with the body for effect.”
Baronius specifically notes that, yes, it was unusual to find a body in a coffin lying on its side, but that’s how it was and that’s how it had been for a long time. There’s no reason to believe that he was lying, or that he wouldn’t have noticed and mentioned any disturbance of the body in the coffin. He goes into great detail about the cypress coffin and its lid, for goodness’ sake!
There’s not any reason to believe that Pope Paschal would have mucked about with the body, either. He found bloody cloths in Cecilia’s coffin, and he put them in with her in the new coffin when he re-buried her. The bloody cloths were still there when her tomb was found and opened.
Legend says that it took St. Cecilia three days to bleed to death. When she died, she probably went into rigor mortis pretty quickly. Since the manner of her death was so edifying and had been seen by so many, it seems likely that the Roman church members would have been reluctant to mess with the evidence of her martyrdom testimony. They didn’t change her clothes, and they just added a shroud on top. She probably didn’t have any food or drink in her, given that her head was partly chopped off. So they wouldn’t have had to wash the body. What other fiddling had to be done? Since she was slim and was in a relatively straight position, why not pop her body into the coffin in the exact position it had at her soul’s entrance into heaven?
In fact, if you read back a bit, you find out that the observers noted that the cypress coffin (inside the marble sarcophagus set there by Pope Paschal) was actually very tiny and skinny, and sized to fit in a catacomb niche. So they went back and re-read what Pope Paschal said about translating the body to St. Cecilia in Trastevere, and sure enough, it sounds like all they did was pop Cecilia’s body out, pop a damask silk liner into the old coffin, and then pop her back in there with a nice silk veil over the body.
There are a lot of accounts, both translated and in the original Latin of the records.
A nice travel blog post showing a lot of stuff in the church and crypt, including the courtyard/garden.