Estimation of postmortem interval based on the third component of complement (C3) cleavage.

To estimate postmortem interval (PMI), the spontaneous conversion of the native third component of complement (C3) to its derived fragments in whole blood was studied by crossed immunoelectrophoresis. C3 cleavages in vitro at different temperatures showed that the incubation of whole blood at a higher temperature led to a faster conversion of beta 1C (native C3) to beta 1A (C3c). In cadaveric blood, we found a significant positive correlation between percentage of C3 cleavage and PMI. From these results, it is possible to estimate PMI from the ratios of C3 cleavage.