Should detectives be sniffing out criminals literally? Could their noses be as useful as their eyes in the hunt for clues?
We are looking to determine the potential of perfume to act as a form of trace evidence. But in order to do so, we need to understand how perfume transfer from one piece of fabric to another. Only when we have an understanding of that, we can assign evidential value to that trace evidence.
And what is trace evidence?
So trace evidence is anything that is found at the crime scene in very small amount. It can be anything from dust, to pollen to gunshot residue.
So these are traditionally physical things but you are looking at a scent.
Yes. Yes. We are looking at scent. For example, there's a lot of studies done on the scent of explosives, of drugs, for example marijuana or cocaine.
Well, you are specifically looking at perfume?
Yes, perfumes are widely used. They are used on a regular basis by both men and women.
We have the analytical technique. And it's a very accurate and reliable technique. So putting these together, we can obtain a lot of information.
And what types of crimes are we talking about here?
It would have to involve contact.
Human to human?
Yes, it'll be physical contact that will involve some transfer of fragrance from one piece of fabric to another or to this kin.
So it will be something like sexual assault or for example a pub fight, anything that involves contact.
And what does your research suggest, I mean how accurate can detectives be in tracking down someone from their perfume?
There are many variables that affect the transfer of the perfume, but also the persistence.
I was looking at for how long a perfume stays on a fabric before transferring. So if the offender had perfume on his fabric that was one day old or seven days old, how that influences the transfer onto a secondary piece of fabric.
So how many days potentially would police forces have for this evidence to be credible?
We saw that after seven days, we found 6 perfume components out of the 44 originally identified in a male perfume.
But to be clear, this is not like DNA evidence.
Yes, I think there is a very clear difference between DNA and all other forms of trace evidence and that would include perfume evidence.
And this will just be one bit of evidence. You suspect that this wouldn't be, you know, the piece of evidence that could be used in court and specifically identify a killer.