Just one example, but there are many:
Person X is missing and reported as such by her husband. The husband has replaced carpeting in the bedroom, but the blood stain is still illuminated with luminol. The area of the blood stain to the volume of blood loss can be calculated to determine that anyone losing that volume of blood would be dead.
Velveeta wrote:
"[Quoting me] 'In the absence of a corpse, how are we to know that a murder has occurred?'
"Just one example, but there are many: Person X is missing and reported as such by her husband. The husband has replaced carpeting in the bedroom, but the blood stain is still illuminated with luminol. The area of the blood stain to the volume of blood loss can be calculated to determine that anyone losing that volume of blood would be dead."
Good example!
The trouble in this case is that nothing equally as inculpatory as a positive luminol reading exists.
JNS