Muscle cells live on for several hours. 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.
Beginning approximately in the third hour after death, chemical changes within the body's cells cause all of the muscles to begin stiffening, known as rigor mortis . 5 With rigor mortis, the first muscles affected will be the eyelids, jaw, and neck.
The formula approximates that the body loses 1.5 degrees Fahrenheit per hour, so the rectal temperature is subtracted from the normal body temperature of 98 degrees. The difference between the two is divided by 1.5, and that final number is used to approximate the time since death.
Rigor Mortis
Slowly over the next 24 to 48 hours the body starts to stiffen (not contract but just lock in place) due to a buildup of acid in the muscle tissues. This stiffening process, called Rigor Mortis, has a roughly known time of occurrence and can therefore be used to estimate 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. The body becomes stiff because of a range of chemical changes in the muscle fibres after death.
These changes unfold quickly, over a few days. Your muscles relax. Your muscles loosen immediately after death, releasing any strain on your bowel and bladder. As a result, most people poop and pee at death.
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.
One of the wildest innovations is “living funerals.” You can attend a dry run of your own funeral, complete with casket, mourners, funeral procession, etc. You can witness the lavish proceedings without having an “out-of-body” experience, just an “out-of-disposable-income” experience.
They might close their eyes frequently or they might be half-open. Facial muscles may relax and the jaw can drop. Skin can become very pale. Breathing can alternate between loud rasping breaths and quiet breathing.
An unexpected discovery made by an international team, examining the results of an EEG on an elderly patient, who died suddenly of a heart attack while the test was in progress.
The physiologic time of death, when the victim's vital functions actually ceased. The legal time of death, the time recorded on the death certificate. The estimated time of death, the time the medical examiner estimates that death occurred.
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.
Calculating Time of Death using Algor Mortis – Page 85
For the first 12 hours after death, the body loses about 1.4° F per hour. After the first 12 hours, the body loses about 0.7° F per hour. These numbers are estimates and vary depending on surrounding temperatures and conditions.
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.
“As soon as the heart stops, you not only lose consciousness and your brain stem reflexes are all gone, but also the electricity that your brain creates slows down immediately, and within about 2 to 20 seconds it completely flatlines.”
For more than 10 minutes after doctors confirmed death through a range of observations, including the absence of a pulse and unreactive pupils, the patient appeared to experience the same kind of brain waves (delta wave bursts) we get during deep sleep.
In the hours before death, most people fade as the blood supply to their body declines further. They sleep a lot, their breathing becomes very irregular, and their skin becomes cool to the touch. Those who do not lose consciousness in the days before death usually do so in the hours before.
In the last hours before dying a person may become very alert or active. This may be followed by a time of being unresponsive. You may see blotchiness and feel cooling of the arms and legs. Their eyes will often be open and not blinking.
Gasping is also referred to as agonal respiration and the name is appropriate because the gasping respirations appear uncomfortable, causing concern that the patient is dyspnoeic and in agony.
Brain activity supports that a dying patient most likely can hear. Even if awareness of sound cannot be communicated due to loss of motor responses, the value of verbal interactions is measurable and positive. Patients appear comforted by the sounds of their loved ones (in person and by phone).
Periods of rapid breathing, and no breathing for brief periods of time, coughing or noisy breaths, or increasingly shallow respirations, especially in final hours or days of life.
At the point of death, muscles no longer work. It takes muscles to open and close eyes. When those muscles relax, a person's eyelids might pop open instead of staying closed.