The ashes, you believe, are the Charizard's strongest efforts to escape. The Charizard must have spewed flames to try and break free.
Taking a look at each of the suspects' feet, you notice that none of their feet are covered in ashes. There are ashes on Blaine's hands, and you try to ask him. "Blaine, how did those ashes get on your hands?" you ask.
"Gumshoe, I was with him all day. His Magmar died, and he tried to save it, but got ashes on his hands." Lt. Surge moans.
"Flametail....." Blaine sobbs, sheading a tear. You can tell that he is not lying, for he carries a picture of his deceased Magmar in the pocket of his Docers.
Examining the fingerprints on the mirror, you notice that they do not match Lt. Surge's, or Giovanni's, but you cannot tell if they match Blaine's, for his hands are covered in ashes.