A body is found lying face-down on the floor of a locked hotel room. The door was secured from inside and there is no second exit. The medical examiner establishes three facts: (1) time of death was between 11 PM and 1 AM; (2) lividity — the post-mortem pooling of blood in the lowest points of the body — is fixed, appearing on the victim's upper back, the backs of the shoulders, and the backs of the thighs; (3) lividity becomes fixed approximately 8 to 12 hours after death. The body was discovered at 8 AM. A detective argues the death cannot be a suicide, based on the forensic evidence alone — not on the locked door. What is the detective's reasoning, and what does the lividity pattern prove about the body's position after death?