Full transcript of Analytical chemist Simona Francese’s TED Talk: Your Fingerprints Reveal More Than You Think.
Listen to the MP3 Audio: Your fingerprints reveal more than you think by Simona Francese
Simona Francese – Professor of Forensic and Bioanalytical Mass Spectrometry
Do you ever stop and think, during a romantic dinner, “I’ve just left my fingerprints all over my wine glass?”
Or, do you ever worry, when you visit a friend, about leaving a little piece of you behind on every surface that you touch?
And even this evening, have you paid any attention to sit without touching anything? Well, you’re not alone.
Thankfully, criminals underestimate the power of fingerprints, too. And I’m not just talking about the twisted parting of lines that make our fingerprint unique. I’m talking about an entire world of information hiding in a small, often invisible thing.
In fact, fingerprints are made up of molecules that belong to three classes: sweat molecules that we all produce in very different amounts, molecules that we introduce into our body and then we sweat out, and molecules that we may contaminate our fingertips with when we come across substances like blood, paint, grease, but also invisible substances.
And molecules are the storytellers of who we are and what we’ve been up to. We just need to have the right technology to make them talk. So let me take you on a journey of unthinkable capabilities.
Katie has been raped and her lifeless body has been found in the woods three days later, after her disappearance. The police is targeting three suspects, having narrowed down the search from over 20 men who had been seen in that area on the same day.
The only piece of evidence is two very faint, overlapping fingerprints on the tape that was found wrapped around Katie’s neck. Often, faint and overlapping fingerprints cannot help the police to make an identification.
And until recently, this might have been the end of the road, but this is where we can make the difference. The tape is sent to our labs, where we’re asked to use our cutting-edge technology to help with the investigation.
And here, we use an existing form of mass spectrometry imaging technology that we have further developed and adapted specifically for the molecular and imaging analysis of fingerprints.
In essence, we fire a UV laser at the print, and we cause the desorption of the molecules from the print, ready to be captured by the mass spectrometer.
Mass spectrometry measures the weight of the molecules — or as we say, the mass — and those numbers that you see there, they indicate that mass.
But more crucially, they indicate who those molecules are — whether I’m seeing paracetamol or something more sinister, forensically speaking.
We applied this technology to the evidence that we have and we found the presence of condom lubricants. In fact, we’ve developed protocols that enable us to even suggest what brand of condom might have been used.
So we pass this information to the police, who, meanwhile, have obtained a search warrant and they found the same brand of condom in Dalton’s premises. And with Dalton and Thomson also having records for sexual assaults, then it is Chapman that may become the less likely suspect.
But is this information enough to make an arrest? Of course not, and we are asked to delve deeper with our investigation.
So we found out, also, the presence of other two very interesting molecules. One is an antidepressant, and one is a very special molecule. It only forms in your body if you drink alcohol and consume cocaine at the same time.
And alcohol is known to potentiate the effects of cocaine, so here, we now have a hint on the state of mind of the individual whilst perpetrating the crime. We passed this information to the police, and they found out that, actually, Thomson is a drug addict, and he also has a medical record for psychotic episodes, for which presumably the antidepressant was prescribed.