1. Lividity
When the heart stops pumping blood through the body, blood will travel in the direction of gravity, pools & the body changes color, especially in parts that are touching the ground.
The pooling of blood in the direction of gravity is called lividity.
Lividity begins to appear about 30 minutes to 2 hours after death and continues to become more apparent and darker for up to 12 hours.

2. The postmortem change in color caused by lividity is called livor mortis (see Figure 6-11).
For the first few hours after death, livor mortis is not fixed.

3. If the area of lividity is pressed, the pressure will push the pooled blood away from the spot.
For a moment, the skin will lighten again. When the pressure is removed, the blood quickly pools again.
After approximately 12 hours, however, the lividity becomes fixed— irreversible and permanent.

4. Because lividity becomes fixed, forensic investigators can use it to determine whether the body was moved after the victim died.

5. Within the first hours after death, patches of lividity in different areas of the body indicate the body has been moved.
After lividity has become fixed, lividity that is not consistent with the position in which the body was found is an indication that the body was probably moved.

6. If an arm or leg is in a hanging position, such as over a bed or chair, when a person dies, petechiae may appear.
Petechiae, small red dots underneath the surface of the skin, occur as capillaries near the skin rupture

7. Livor mortis
A bluish-purple or reddish-purple color on parts of the body closest to the ground or floor.
The color becomes darker as time passes because after death, oxygen begins to separate from hemoglobin. This change produces a purple pigment— deoxyhemoglobin—in the red blood cells.
Areas away from the ground and at the edge of the lividity tend to be pink.
However, variations in the color of the lividity can provide clues to the cause of death.

8. Livor mortis
Ex. victim of carbon monoxide poisoning is likely to show bright red lividity. Because cold temperatures slow the formation of deoxyhemoglobin, lividity in a victim of hypothermia will be bright pink.
A body refrigerated shortly after death and the body of a victim of cyanide poisoning also exhibit bright pink lividity.
Dark brown lividity indicates exposure to lethal doses of nitrates, aniline, and potassium chlorate. (herbicides)

9. Crime-scene investigators sometimes misinterpret lividity as bruising or signs of trauma. In such cases, an autopsy easily confirms the discolorations as livor mortis.
Bruising is the result of blood leaking into extracellular spaces—the spaces between cells.

10. Bruising is often the first visual sign of trauma.
If the discoloration is indeed lividity, the blood will be confined to the blood vessels.