A detective arrives at the scene of a suspected self-inflicted death by fire in a remote location. The victim's body shows severe burns to the front, but the back is largely intact. The medical examiner finds fine black soot deep in the bronchioles — the smallest airways of the lungs. A large quantity of sleeping medication was found in the victim's stomach, partially absorbed. The detective immediately tells the responding officer that this is not a straightforward suicide. Her colleague argues that the pills alone prove suicidal intent. What is the detective's single strongest counter-argument, and what does the soot finding specifically prove about the sequence of events?