Bone and skin cells can stay alive for several days. It takes around 12 hours for a human body to be cool to the touch and 24 hours to cool to the core. Rigor mortis commences after three hours and lasts until 36 hours after death. Forensic scientists use clues such as these for estimating the time of death.
For approximately the first 3 hours after death the body will be flaccid (soft) and warm. After about 3-8 hours is starts to stiffen, and from approximately 8-36 hours it will be stiff and cold.
What Happens One Hour After Death? At the moment of death, all of the muscles in the body relax (primary flaccidity ). The eyelids lose their tension, the pupils dilate, the jaw may fall open, and the joints and limbs are flexible.
For the first few minutes of the postmortem period, brain cells may survive. The heart can keep beating without its blood supply. A healthy liver continues breaking down alcohol. And if a technician strikes your thigh above the kneecap, your leg likely kicks, just as it did at your last reflex test with a physician.
Livor mortis begins appearing as dull red patches after 20 to 30 minutes from the time of death. Over the next 2 to 4 hours, the patches come together to form larger areas of bluish-purple discoloration.
3-5 days after death — the body starts to bloat and blood-containing foam leaks from the mouth and nose. 8-10 days after death — the body turns from green to red as the blood decomposes and the organs in the abdomen accumulate gas. Several weeks after death — nails and teeth fall out.
By three days, internal organs have decomposed. From three to five days after death, the body will begin to bloat from gasses produced from internal decomposition. The body could actually double in size and turn a greenish color. Extremely unpleasant and long-lasting odors called putrification begins.
The first visible change to the body—occurring 15 to 20 minutes after death—is pallor mortis, in which the body begins to pale. Pallor mortis occurs because blood stops moving through the capillaries, the smallest of the body's blood vessels.
The brain and nerve cells require a constant supply of oxygen and will die within a few minutes, once you stop breathing. The next to go will be the heart, followed by the liver, then the kidneys and pancreas, which can last for about an hour. Skin, tendons, heart valves and corneas will still be alive after a day.
Although death has historically been medically defined as the moment when the heart irreversibly stops beating, recent studies have suggested brain activity in many animals and humans can continue for seconds to hours.
Putrefaction (4-10 days after death) – Autolysis occurs and gases (odor) and discoloration starts.
Pupils dilate
When people die, their bodies relax. This impacts your eyes just as much as the rest of your body. As soon as the muscles that control your eye movement relax, the pupils dilate. This happens over a progression of several hours after death.
As the blood pools, patches appear on the skin within 30 minutes of death. About two to four hours postmortem, these patches join up, creating large dark purplish areas towards the bottom of the body and lightening the skin elsewhere. This may be less apparent on darker skin. This process is called livor mortis.
An accurate time of death also can help rule out possible suspects who may have been somewhere else when the death occurred and a more general time range could create a larger window for someone's alibi. This information can be used in court to establish a case.
Changes in the muscles: Immediately after death, the muscles undergo primary relaxation, as mentioned above, which is followed by stiffening of muscles known as rigor mortis. With the onset of putrefaction, rigor mortis passes off, and secondary relaxation occurs.
It is a common practice to cover the legs as there is swelling in the feet and shoes don't fit. As part of funeral care, the body is dressed and preserved, with the prime focus on the face. Post embalming, bodies are often placed without shoes; hence covering the legs is the way to offer a dignified funeral.
Your brain stops. Other vital organs, including your kidneys and liver, stop. All your body systems powered by these organs shut down, too, so that they're no longer capable of carrying on the ongoing processes understood as, simply, living.
Visions and Hallucinations
Visual or auditory hallucinations are often part of the dying experience. The appearance of family members or loved ones who have died is common. These visions are considered normal. The dying may turn their focus to “another world” and talk to people or see things that others do not see.
Agonal breathing or agonal gasps are the last reflexes of the dying brain. They are generally viewed as a sign of death, and can happen after the heart has stopped beating.
Lung - 4 to 6 hours. Heart - 4 hours. Liver - 24 hours.
After death, there is are no reflexes of the pupils to light and the cornea also loses its reflex. The cornea of the deceased also become cloudy after two hours of death. Besides that, the pressure in the eyes start to decrease and the eyeballs become flaccid before it they sink into the orbits of the eyes.
In time, the heart stops and they stop breathing. Within a few minutes, their brain stops functioning entirely and their skin starts to cool. At this point, they have died.
However, on average, a body buried within a typical coffin usually starts to break down within a year, but takes up to a decade to fully decompose, leaving only the skeleton, Daniel Wescott, director of the Forensic Anthropology Center at Texas State University, told Live Science.
After 1 month, the liquefaction process commences. During this stage the body loses the most mass. The muscles, organs and skin are liquefied, with the cadaver's bones, cartilage and hair remaining at the end of this process.