A 58-year-old man is discovered dead in a house fire. The body shows extensive charring with blackened, brittle skin that cracks and peels off easily. The subcutaneous tissues are pale and unaffected. On examination of the airways, no soot or carbonaceous material is found. Carboxyhemoglobin levels are measured at 2%. The abdomen is distended with gas, and there is early decomposition. What is the most likely conclusion regarding the timing of the burns?