A 32-year-old man is found dead in a burnt house in Delhi. The body shows extensive charring of the skin with a dark brown to black appearance. On examination, the pathologist notes that the skin is dry and leathery, with no blistering. The muscles beneath show a deep red discoloration. There is no soot in the airways or lungs. The blood carboxyhemoglobin level is 2%. Which of the following is the most likely scenario?