I thought with two weeks of 'vacation' I could do a little more with this blog. However, finishing my novel proved to be more work than I expected! Regardless, here it goes.
Other than 'what's the most disgusting thing you've ever seen?' the question I get asked most frequently is 'how can you tell how long someone has been dead?' There are many things I take into account when determining how long someone has been dead. Most commonly I use livor mortis, rigor mortis, and algor mortis.
Livor mortis is the redish discoloration that appears on a body due to the gravitational pooling of blood. It's sometimes called lividity. Once the heart stops pumping the blood travels in the direction of gravity and starts to collect in the dependent region. Areas of the body that are pressed up against an object, like the floor or a bed, leave white 'blanched' spots because the blood can't get there. Lividity can altered by changing the position of the body. After about 12 hours it 'fixes' and no longer moves around. This means if you find a body before 12 hours and move it, the lividity will change position. It does this because the blood, although not being pumped by the heart, is still liquid, and will flow towards the new direction of gravity. BUT, after around 12 hours if you move the body the lividity will have become fixed and will not travel towards the new dependent area and I will know someone moved it! There is a gray area around 12 hours where there may be two patterns of lividity. This happens because the blood is moving slowly and hasn't had time to relocate yet. It still tells me that the body has been moved. There are a couple of interesting things about lividity. One. it happens quickly, almost immediately after death. It has even been reported in elderly people in heart failure. Second, the color of the lividity can sometimes help you determine the cause of death. They typical color is purple. Cyanide and carbon monoxide can make lividity pink and cherry red, respectively.
Rigor mortis is the postmortem stiffening of the body. It happens because the muscles are no longer making ATP, which is the chemical that supplies energy to the muscle. Without ATP, the muscles can't relax and they get stiff. Rigor is dependent on a number of factors such as body temperature, room temperature, and the temperature outdoors. It's highly variable. Interestingly, rigor fixes, or becomes 'stuck' after about 12 hours, too. So, if you find a body before 12 hours and move it, and then leave it, the rigor will cause the body to fix in the new position that it's in; again, if you find a body after 12 hours and move it, the rigor will have 'frozen' the body in the original position and I will know you moved it! It's not uncommon for someone to find a dead body in bed, face down, with the arms hanging; the person will roll the body over to check for a pulse. Rigor will have set in and the arms will be sticking straight up in the air. I will know someone moved the body. Rigor vanishes after about 36 hours. This is because the muscles decompose and turn to mush.
Another thing that is sometimes used is algor mortis. Algor mortis is not what happened to Al Gore's political career after his loss in the presidential elections, it's the loss of body temperature. I do have to say that the name is ironic given how Al Gore was so concerned with our global temperature. The body will lose about 1.5 to 2 degrees celsius per hour. Again this is HIGHLY variable and dependent on so many factors such as initial body temp, the room temp and the outside temp. It's not really used that much anymore.
So, what do I do? I use these simple little rules, and despite what you see on TV, it's the best science can do! If you find a body, don't touch it. But, these are my rules:
If a body is warm and flaccid, it's been dead less than 3 hours.
If a body is warm and stiff, it's been dead between 3 and 8 hours.
If a body is cold and stiff, it's been dead 8 to 36 hours.
If a body is cold and flaccid, it's been dead more than 36 hours.
