Tales of a forensic ecologist — tracking criminals with pollen and spores

Originally published on December 21, 2019.

Back in the early '90s, Patricia Wiltshire, professor of environmental archeology from the University College London, already had a career. She used her expertise to help reconstruct the distant past, to help understand how people lived centuries ago.  

And then, one day in 1994, the phone rang and she entered a new world. It was a world more familiar from Agatha Christie or Sherlock Holmes or the CSI television series — a world of crime, violence and death.

It was a surprising transition. Wiltshire's expertise wasn't in dead bodies or murder weapons. It was in things like plant pollen and fungal spores.

"I was an ecologist and a botanist working in archeology doing environmental reconstruction of the past. And you can do that by looking at plant remains from the past, both the big bits — leaves, stems and so on — that get deposited into pits and ditches, but also pollen and spores that fly around in the air and get deposited in sediments," Wiltshire told Quirks & Quarks host Bob McDonald. 

If you can see a scenario in the past from vegetation, why can't you see a scenario from the present from vegetation?- Patricia Wiltshire, author of The Nature of Life and Death

Wiltshire spoke about the turn her career took as she pioneered the new field of forensic ecology in the United Kingdom. She recounts this tale in new memoir, The Nature of Life and Death: Every Body Leaves a Trace.

The interview below has been edited and condensed.

Tell me about that phone call you got back in 1994 that became such a turning point in your life.

Well, I was sitting at my microscope counting pollen, which is a very tedious task I must say, and the telephone went. There was a very Scottish voice at the other end. And he said, "We would like you to do a job for us? We've been to Kew Gardens, the Royal Botanic Garden. And they said they can't help us, but they know a woman who could. And so they've given me your name." And this was quite intriguing. I don't think I've ever spoken to the police before. So they said, "We have a murder." Well, that got me hooked immediately. 

What made you believe that you could apply your experience reconstructing the past to help solve a murder investigation?

Well, to be honest, I didn't know I could. But when you think about it, if you can see a scenario in the past from vegetation, why can't you see a scenario from the present from vegetation? 

What did you do then to go collect evidence to help them solve the crime? 

The senior investigating officer had a thought that pollen might be able to help this case. And what had happened was there was a Chinese Triad gang. They were money laundering and doing that, they were buying properties, but they needed an agent. They chose an agent. He had all the money. He was supposed to buy properties and fiddle around with the money. But he helped himself to it. And of course that didn't go down very well with the Chinese Triad. 

They kidnapped this man on his wedding day. They tied him up, putting his arms and legs behind his back, put him in the back of a van. And he was a big, heavy man. And his lungs collapsed and he died. And they panicked. And so, they thought, "Oh gosh, we'll have to get rid of the body. We'll go and dump it in Wales." But they couldn't find Wales, so they set off in this van northwards and ended up in Hertfordshire. They saw what they thought was a very secluded place, drove into the field and dumped the body.

The police got the van. There was also an accompanying car and they had seen the tire marks in the field. And they wanted to know whether this car had been in this field. Well, they didn't know how to prove this because tire marks are not as resolved as you might think sometimes. But this clever police officer thought, "Oh, this field has been planted with maize, with corn. I bet there's pollen and perhaps they've taken it back to the car." 

So they asked me to look for corn pollen, for maize pollen, in the car. I did not have a clue how to go about it. So I had the car taken completely to bits and I analyzed just about everything.

There was no maize pollen because this was in the spring and maize doesn't flower until later, so the pollen wasn't there. But what they did do, was they stepped on the field edge to put the body in the ditch. And that field edge, and all the pollen from the hedgerow that was at the back of the ditch, they'd carried all that back to the car. And I was able to see this place in my mind's eye. 

It gives it a holistic picture of the environment because plants respond to their environment.- Patricia Wiltshire, Author of The Nature of Life and Death

And so [the police] asked me if I'd like to go and see the place. And when I got there, the field was absolutely huge. And it had this very ancient hedge all the way around it. And they said, "Oh, we'll show you where the body was." But I said, "Well, let me just test myself and see if I can tell you." And I walked up the hedge. It wasn't the right place, it wasn't the right place, and then all of a sudden, it was.

All those herbaceous plants, all of those weeds that you see typical of arable fields were there, and specifically an assemblage of shrubs that were growing in the hedge. And they were all there. And I said, "I think this is the place." And everybody fell over, practically, because it was exactly where the body had been put. And nobody was more shocked than I was, that I was able to do that.

What does that say to you about just how much potential this microscopic evidence has that's out in the environment to track down someone?

It's incredibly powerful. If I get the assemblage of plants from their pollen or from their spores, I can envisage a plant community. Now I can't always describe where [it is], but I can describe the place. However, if I can recognize a specific habitat, I can predict the soil and therefore I can predict the geology. So it gives it a holistic picture of the environment because plants respond to their environment. 

What is it about pollen grains and fungal spores that make them such potentially potent and durable pieces of microscopic forensic evidence? 

First of all, they're tiny. The biggest pollen grain I can think of is about 110 microns. If you've got eyes like a hawk, you might just be able to see that with the naked eye. But most are about 40 microns, absolutely tiny. And the other interesting thing about them is that they're charged particles, so they stick to things. And when it comes to fabric, they will wiggle down into the weave of the fabric. It's jolly difficult to get them out. They can be there for years and years and years.

How many branches of science have come together for you to build what you call, "informed intuition," to build up this image in your mind of the place you're looking for? 

Well, an ecologist really has to be a jack-of-all-trades, as well as a specialist. Ecology is the study of organisms and their environment — everything. So one needs to know about plants, animals, bacteria, fungi, the substances in the soil, chemistry, statistics — you need you need very, very many strings to your bow. And you never, ever, ever stop learning.

What does that feel like you come up with the picture of the place in your mind where you go, "Oh I know where this is"? 

It's more than that too, because sometimes you can see a sort of trajectory; you can see that someone has walked here first, then walked there and then there. As you can imagine yourself, if you walk in any woodland, you know very well that as you walk through that woodland, the scenario changes a little bit. And you can actually see that deposited on the shoe or on the clothing. And in fact, I can get pollen from just about anything. It's in your hair. It's up your nose. It's on your clothes. It's under your fingernails. We've all got pollen on us and inside us, even [in] your gut. I mean I've done a lot of gut analysis. It's a rather messy, nasty procedure, but boy, it gives you results.

What do you see as the difference between what's portrayed in forensic crime fighting programs and reality?

Oh huge, huge differences. I expect you know the American program, CSI? Well, an awful lot of that is just mythology, really. The forensic work is not glamorous. What I do is tedious, hard, smelly, disgusting and the only satisfying part is when you get the patterns at the end of your analysis and you think, "Gosh, I can see it, I can see it." That is the reward.

These forensic programs, I don't watch them really. They just get on my nerves because they're just not accurate enough. A forensic scientist has to be accurate. That makes us, perhaps, a little bit boring and TV can't afford to be boring, can it? 

What do you hope the reader takes from your book when it comes to appreciation of the microscopic world that surrounds us and our environment? 

You know, the microscopic world is wonderful. And I love looking at microscopic things. I always have. Perhaps, what I'd like them to realize, is that the world is unbelievably complicated — much more complicated than anybody would ever think.

Produced and written by Sonya Buyting