Estimating the Postmortem Interval ANA315 Time Since Death Estimating the Postmortem Interval ANA315

Colonel William Shy 1838-1864 Open mind All evidence should be considered before a conclusion is reached.

“Body Farm” University of Tennessee at Knoxville 3 ac of land, fenced, wooded Experimenting with the rates of decomposition Founder= Dr. William Bass

Decomposition Change in an organism from one state to another via chemical processes

Techniques for PMI Body temperature Rigor mortis Lividity Vitreous Humor Putrefaction Entomology – most reliable method(Dr. Mervyn Mansell)

Algor mortis

Rigor mortis Onset and duration =environmental temperature and degree of muscular activity before death First appears in the eyelids and moves to the lower jaw, neck and limbs Re-establishment of rigor

Lividity –Livor mortis Dark purple discoloration of the skin caused by pooling of blood 10-12 h lividity becomes fixed; movement of the body will create ‘primary’ and ‘secondary’ patches of lividity.

Vitreous Humor Linear relationship between potassium concentration of the vitreous humor of the eye and PMI Normal distribution = confidence levels are high and thus the method has no real practical application

Putrefaction Initial decay Early putrefaction Black putrefaction Butyric fermentation Dry decay Skeletonization