How Entomologists Use Insects to Solve Crimes

[suspenseful music]

[Instructor] [camera clicking] See this fly?

It's a floored fly, also known as a coffin fly.

Flies like these provide crucial evidence

in solving mysterious death.

Insects never lie.

Insects are tiny witnesses.

With my job as forensic entomologists

I use these tiny witnesses to give justice to victims.

[Instructor] Wired spoke with Dr Paola Magni

to understand how insects can be used

to help solve suspicious deaths.

[upbeat music]

The forensic entomologists is one of the many experts

that work at the crime scene in order to provide

more information to the course of an investigation.

The postmortem interval or PMI is considered

the time since death.

It is pretty much the time between the moment of death

to the identification of a dead body.

They can provide an alibi to somebody

or destroy an alibi for somebody else.

Turn Italy, case one.

The victim was a female that was found

wrapped in a blanket and covered by a carpet.

The pathologist could not estimate at time since death,

the body was highly decomposed.

Typically, the pathologist work within the 72 hours

after death.

After this time, nature takes over

and the typical signs of that, the rigor mortis,

algol mortis, liver mortis cannot be used anymore.

But this is exactly the perfect time for the insects

to colonize the body and start what we call

the biological clock.

That is what forensic entomologists use

to investigate and estimate the time since death.

[Instructor] Estimating the PMI in this case

relied on analyzing the life cycle of flies

through development from egg to adult can be predicted

based on environmental conditions.

Insects grow faster or slower

based on the environmental temperature

and there were maggot masses active on the body.

So if outside there were 25 degrees inside

of the maggot mass nearly 28 degrees.

My job in that case was to collect the maggots,

considering the species and temperature

to backtrack the time since death.

That case was very complex.

There was already somebody suspected of this murder

but the insects were giving different information,

giving an alibi to this suspect.

The time since that was around the same time

of a long exchange of messages and phone call

with a certain person helped the investigators

investigate specifically on someone else

asked the right questions and close the case.

Turn Italy, case two.

Some insects are interested in the fresh decomposition,

some highly decay, and some when body is just bones.

Based on the kind of insect I can find,

I can can understand from how long the body's there.

So my job was to participate into the investigation

if this person was dead since the last time

he was seen alive or if there was something going on.

The body was nearly mummified by the bugs

and specifically one type of that are called

the larder beetles created a very strange structure.

They were looking like threats on the body.

When the body is mummified or when I find just bones

on a very old body, I use another technique

that is called a successional waves methodology.

[Instructor] Successional waves refers

to the different types of insects that are found

at different stages of decomposition.

Using this method allows forensic entomologists

to estimate PMI for older cases.

The case of the forgotten man was pretty complex

because there was an association

of different type of insects.

We had to identify which insects were belonging to the body,

and which one to the house.

All of these insects were giving us information

about how many successional waves had passed by

to estimate the time since death.

We realized that the body was laying

in the place where we found it for at least

a year and a half.

[Instructor] Western Australia, case three.

When we watched CSI or similar TV programs,

most of the time investigators found

the presence of a body on the ground.

Reality is that the majority of the cases,

bodies are found contained in something.

We consider that as limited access environment.

Insects have a physical impediment to reach the body,

but they don't give up.

Insects really try their best to reach the body

because the body means food, and the body means

place for the offsprings to grow and survive.

Blow flies will lay eggs on the zip

and the female of coffin flies can pass through the zip

and reach the body.

So there is this consuming food chain

that happened inside of a suitcase that is very interesting

because what we find inside is whatever happened before.

So we can find different successions,

and we can work on that to identify from how long

the body is inside of a suitcase.

Despite these cases happen all around the world

and pretty often, the research is really scanned

because it's very difficult to perform such a huge research.

My group of research is developing this to find out

how insects can interact with a body during

the winter period in suitcases compared to trash can.

These research will allow us to give more information

to investigators if cases like this happen

in Western Australia.

Forensic entomology is really holistic

from the point of view as a discipline

because you consider insects, also had to consider

the investigative process, and has to combine

the information from the insects with the information

about the environment, the methodology

and at the specific crime scene.

What I'm trying to do with my work

is to use this little piece of nature

to give justice to the victim.

[camera clicking]