Q: I’m writing a young-adult novel set in the ancient Roman world. My “detective” is a slave girl without medical training but who has lived on a farm and observed animals being butchered. I need her to be suspicious about the reported time of death of a woman, based on the state of the body and the condition of the blood (the woman’s throat was cut and blood is still dripping off her bed when she is found). What would be the timeline of rigor mortis, and how long would the blood remain liquid? Are there any other clues that would lead her to suspect that the woman was killed very recently, and not several hours earlier, as was reported?
Tracy Barrett, YA author
A: Once blood leaves the body it begins to clot very quickly. This process is completed in 5 to 10 minutes. After that, the blood begins to separate as the clot retracts into a dark knot and squeezes out a halo of yellow serum. This process would take another hour or more. The blood will then dry to a rusty brown stain. This could take several hours or even days in a moist climate.
You’re young slave girl could know this from her experience as a butcher. If she found blood that was liquid and still dripping she would know that the murder took place less than 10 or so minutes earlier. If she found that the blood had clotted but not separated then she might conclude that the murder took place more than ten minutes but less than an hour earlier. If the blood had separated into a clot and a surrounding halo of yellow serum, she would guess that the death occurred somewhere between one and three hours or so. Finally, if the blood had completely dried she might conclude that the death occurred at least 4 to 6 hours earlier, or longer in a moist environment. These are very general but should give you a usable timeline.
Rigor mortis would not play a role here since your corpse is found fairly quickly after death and it takes about 12 hours for rigor to fully develop. In this situation, the blood would more clearly define the time of death.