A little more about forensic entomology...

What techniques are used to determine the time since death to the finding of the body?

There are two methods of determining the time since death to the finding of the body:

• Entomological succession;

• Age and the development of larvae.

The first, is used when death was about a month or more. We require an advanced knowledge about the development of insects. It is necessary to know their cycles and when each insect appears.


The second method is used when the interval between the discovery of the body and death is less than one month. They are considered the first species that come to the site, the varejeiras (flies that lay eggs which then develope). You must have the knowledge of the cycle of these insects to be successfull in this method.





Relation to other areas

A forensic entomology is related to other sciences, but especially with:

• Toxicology - Related to the manner of death (determines the development of certain insects);

• Anthropology - The two sciences act together effectively when the time between death and the finding of the body is quite large;

• Legal Medicine - where the insects are found on the corpse and are directly related to the crime, for example, murder, rape or suicide (entomology legal-medicine).



Sources: National Geographic Magazine - September 2007 "The Science of crime" Http://www.pericias-forenses.com.br/entomo.htm

Written by: Ana Esteves

Translated by: Teresa Felgueiras

What is needed in this area to be used sucessfully?

The establishment of biological clocks is crucial.
To be successfull in this area it is necessary to:

• study the insects that colonize the corpse in their various states of development (eggs, larvae, pupae and adults);
• study what is the pattern of succession, or at what stage of decomposition different species appear in the body;
• Learn how long these insects remain in the corpse;
• Know which are the dominant species in each season of the year (also monitoring their life cycle).

In the study of this science are generally used large animals such as piglets, as this species is more similar to humans, in the pattern of decomposition. To answer the question: "occurance of death" the experts have to assess the evolution of cadaverous stiffness, cooling of the body, deposits of organic matter from the body and evolution of the stages of decomposition of cadaverous fauna. With the aid of this area, the calculation of the value of the IPM (post mortem interval)is easier because, the larger the interval, the more secure is the estimate, unlike the other methods. Thus, all the facts mentioned above are essential to determine the IPM.

Below is a video, of the decomposition of a piglet. We advise people who are more sensitive not to watch the following movie:





Video Sources: National Geographic Magazine - September 2007 "The Science of crime"

Written by: Ana Esteves

Translated by: Teresa Felgueiras

Results of the poll!

There are four stages of development of the flies:

Eggs - are tiny. Normally present as agglomerations a wound or hole natural;

Larvae - Form of an animal in development (flie, who have not yet reached sexual maturity), other than the state adult;

Pupae - It is the intermediate state between the larva and adult status;

Adults - Those who reached the reproductive capacity (at the level of entomology, the least important).

The question of the first poll related issues important to forensic entomology was: "What is the second stage of development of insects that appear at the corpse?". The results obtained in the poll were:

Larvae - 18 votes;

Pupae - 19 votes;

Adults - 2 votes;

Eggs - 1 votes.

We can conclude that our readers were among two of the options raised. The correct answer was larvae, which wasn´t the most voted option. The most voted was pupae. We hope you continue to participate in our polls and show your wisdom!

Forensic entomology

What is it?

The word entomology comes from two Greek expressions entomon and nology, whose meaning is insect and study respectively. So, entomology is the science that studies the insects.

So, what is forensic entomology?

Forensic Entomology is the science that, studying the insects of a body, identifies the causes of death of human beings. It is used with time of death up to 3 days, as there other methods equally effective when the range is shorter. After three days, the evidence provided by insects are often more valuable, and sometimes the only method of determining the PMI (post mortem interval).



Some applications ...


This area of forensic science has several applications, although it is not very used. It serves to:


- Know the place of death - You can check the place where the death occurred through geographic distribution, natural habitat and biology of the species collected at the scene of death.

- Find the mecanism of death -There are drugs and toxic substances on the body that affect the speed of development of necrophagous insects. Some affect the development of larvae and decomposition of the body, other prevent the colonization of the body by some necrophagous insects.

- Calculate the PMI.

- Know if there were drugs involved - it is possible to identify the origin of some type of drug based on the identification of insects accompanying the drug, which at the time of pressing the plant were retained there, tracing the route of trafficking through the geographical distribution of the same .

- Know if there was abuse - it is possible to determine the number of days during which the baby was deprived of care, hygiene, relying on the determination of the age of the larvae of flies found in beds.

Sources: http://pt.wikipedia.org/wiki/Entomologia_forensehttp://www.pericias-forenses.com.br/entomo.htm

Written By: Ana Esteves

Translated by: Vera Gonçalves

This month

During this month we will be talking about an area of forensic science of which very little is known in Portugal: Forensic Entomology. Although very little is known it includes many aspects of which could be the only method to determine the parameters essential to the developement of all the investigations. Beside Entomology we are going to talk of an area commonly used in our country: forensic toxicology. This broaches various mystries that generally we don’t think that they exsist. Wait for the next few posts and don’t forget to vote on our question...........

Written by: Ana Esteves

Translated by:Teresa Felgueiras

Resume of the Month!

During this month, the group BI126 was very active.

One of the activities was the preparation of the visit to a primary school that makes part of our school, where we perform laboratory work with the students. It was necessary to test all the experiences, prepar posters, bring the theoretical basis to track age of the students... Here are some pictures of these activities:

Another activity was a visit to the scientific Police to Porto. In this activitywe invested some of the funds raised during the search for sponsorship!

Before the visit, there was a preparion of the issues we would like to ask. Then on the day of the visit, after a tour to Casa da Música (Music House) and a beautiful lunch in the Ribeira, we went to the desired location where we had the opportunity to talk with an expert and clarify all our doubts. Furthermore, we had the pleasure of getting to know students from other parts of the northern region of the country which, coincidentally are developing the same theme as us.

Here are some photos of the visit. Unfortunately it was not allowed to capture images inside of the building of the police, therefore you can se a picture of our group in front of Casa da Música , another outside the building of Scientific Poilice and a last of the girls in our class (we all followed ) on the streets of the city.

Written By: Vera Gonçalves

Translated by: Vera Gonçalves

The Fatal Cure - part 5

Investigation doesn’t stop and the curiosity in solving this crime increases every clue, every trace. This time it is Forensic Medicine that will make its contribution! After visiting the crime scene and confirmed the death of the victim, the doctor works in the morgue. The autopsy is the next step! First the external test and then the intern! The corpse is in a state of universal muscle stiffness and has recent injuries in the lumbar and the scalp. This shows that he was attacked by the back. I would even say it might be assaulted with a bat. This made him be unconscious, but was not the cause of death. The skin in the knees is red, as if he had been dragged. There are still traces of semen, which shows that he had a sexual relationship recently. No more unusual aspects were found outside the body, in addition to the normal phenomena post-mortem. Then comes the internal test! The temperature of his liver indicates that he should have died for 17h 00m of that fatal day. All the organs had a morphology within the parameters of normality which suggests that the cause of death is a cardiac arrest. Certainly, the victim was poisoned. However, only we just can indicate the poison with the opinion of toxicologist. The study of suspects continues. Do not miss the next step!!!!! (the movie isn't available in the English version. Watch it in the Portuguese Version. The voice is telling us the text that you can read here)