Livor mortis- setting of blood in the lower portion of the body leaving a purplish red discoloration to the skin, takes 2-8hrs
Algor Mortis- the change in body temp following death.
Rigor Mortis- the stuffing of the skeletal muscles after death
Algor, Livor , and rigor Mortis can be used to estimate PMI by knowing how long ago the person died. By how stiff the corpse is, the cold body temperature, and either the discoloration of the skin.
Other changes to the body after death to determine the PMI would be to check out the stomach contents and changes to the eyes. For the stomach it takes 4-6 hours for the stomach to empty the contents to the small intestine. It then takes another 12 hours for the food to leave the small intestine. Approximately 24 hrs. from when a meal was eaten until all undigested food is released from the large intestine.
Another change in the body would be to the eyes. A thin film is observed within two-three hrs. if the eyes were open at death. If the eyes at death were closed then it would take 24 hours to be covered in the film.
A man was walking home from work when out of nowhere a dog attacks him. Leaving him in critical condition. The man died 5 days later. Prior to this, the man also had AIDS.
Cause: the injuries of the dog attack.
Mechanism: the man had AIDS leaving his body unable to heal.
- Introduction & Hypothesis:
- Hypothesis : I believe that the blow fly process from egg to adult would go faster than the book expected it too. (Click on Hypothesis link to see full hypothesis in detail.)
The importance of this experience is to show how insects help with the decomposition process. Also, this shows how when something dies new life is formed.
The idea of Post-mortem Interval (PMI) is to read and understand the blow fly cycle, someone may have died and determine the time of death from the age of the maggot/blow fly.
Materials & Procedure:
Description: Only after about 8 hours of our raw chicken rotting in the sun, we observed that our chicken had eggs/larva. The eggs and larva are usually found in moist warm areas of the body. These eggs/larva looked like small rice crispy’s. Next in the blowfly cycle is the was the maggot stage, this stage lasts for about 3 days and the maggots feed actively The maggots are hatched from the eggs. Once the maggots are done feeding at around day 5 of the cycle they turn to pupa. Once the pupa’s are done growing they become blow flies. These blow flies are incapable of flight for the first few hours but then shortly after they are on there way to a brand new life. This whole process is expected to take 21-24 days.
My results of this experimented are embedded in the text of the description.
Here are the measurements of our maggots just before they went into the pupa stage. As you can see they are about 2cm long.
My Hypothesis was CORRECT. It was originally estimated in the text book that the blow fly process would take 21-24 days as shown in the chart. When we went out and did the experiment on our own it only took 15 days.
If I could repeat this experiment I would definitely bring a bigger container to put more chicken in. I would also check the chicken everyday instead of every other day. To modify this experiment if we could go to an open field and observe the chicken or other animal in the decomposition process. With all of the elements of nature. The experiment would have been more real instead of our chicken being in a container where nothing but flies and other small insects could get to it. Not just insects help with the decomposition process.
I learned so many things from this experiment. I learned that it only takes a few hours for blow flies to lay eggs, and they usually lay the eggs in an opening in the body. I also learned from this experiment is that the smell is very over powering, more than I expected. I had instant watery eyes after smelling the chicken. The most important thing that I learned is that knowing the life cycle of the blow flies can and what stage they are in can tell you how long ago that something had died. You can solve crime scenes like this and it is a very important resource to have.
This is the blow fly chart from egg to pupa and the time it is expected to take.
After the maggots became full grown they went into the pupa stage. This is the last stage into becoming a blow fly.
Our chicken had more maggots than last time. About 4 more maggots. The temp was high 80s.
Our chicken has completely turned into mush. Unfortunately we did not find any maggot cocoons. What we did find were only two maggots remaining, That were about 1cm long. The smell of our chicken is starting to subside, compared to the first couple of days into this experiment. The temperature is low 90’s, our container was very hot when we grabbed it. Which is making smells a lot stronger and the process seem to go faster.