Adventures in geoforensics

Scientists using 3D imagery

Scientists using the GeoVisionary technology

8 July 2011 by Marion O'Sullivan

Most people have heard of forensic science, made popular by TV dramas like CSI and Cold Case. But the contribution of organisations like the British Geological Survey (BGS) - better known for responding to natural disasters - remains behind the scenes. Marion O'Sullivan finds out how BGS geologists turn detective.

It's five o'clock on a Friday evening and scientist Julian Trick is thinking about calling it a day when the phone rings. It's the UK police National Search Adviser, Mark Harrison, and he needs some expert help on a case.

"Mark always rings at five o'clock on a Friday," says Trick. "When he calls us he's usually working on an old case that hasn't been solved. There are limited resources available for these cold cases, and no real urgency, so he takes them forward whenever he has a spare moment - usually evenings and weekends. He likes to have a single point of contact at BGS - me - and then I contact the relevant people to work with him."

Professor Mark Harrison is a senior police officer and a professor of geo-forensics. He has worked with BGS scientists for a number of years, so when he's called in to solve this case he knows they will be able to help. Unusually, this time it's not a cold case but a current investigation.

A man has disappeared without trace and has been missing for several weeks. The local police suspect murder and have made an arrest - the suspect denies being there, but a smear of his blood has been found at the missing man's home. But what has happened to the man - and if he is dead, where is the body?

This was the dilemma police faced on the remote Orkney island of Sanday in 2009. Under Scottish law there can be no murder conviction without a body. Police found sand on the suspect's vehicle and thought that he and an accomplice had buried the body, but there was no other evidence.

Harrison knew that BGS would be able to help, by finding the origin of the sand found on the vehicle, and identifying the most likely places a body could be buried. The scientists produced a geological map of the island, overlaid with maps of sand and soil types, roads and urban areas. Then, using a colour-coded system they and Harrison had developed, they created a RAG map (Red/Amber/Green) with green areas representing the hardest, least accessible soils (the most unlikely places to hide a body), amber areas showing possible places to dig, and red showing the most obvious areas to search.

"When I phoned BGS that Friday I didn't tell the scientists what I suspected as that might have contaminated their thoughts and led them in wrong directions," says Harrison. "So I only told them what they absolutely needed to know. Because this was an active investigation some of the details were confidential anyway, and I didn't want them turning into amateur detectives and trying to solve the case for me."

An example of a RAG map

An example of a RAG map

Within an hour, forensic geoscientist Russell Lawley and his colleagues had emailed the RAG map to Harrison.

"Using geology is not about trying to find the needle in the haystack, but trying to reduce the size of the haystack," explains Lawley. "Our map played a small role in this case as Mark was also using other detection methods, such as thermal imagery and a dog that had been trained to find bodies. The map showed the most likely place to look and, once the search was switched to that area, the cadaver dog very quickly found the victim's body buried in a shallow grave."

"This case was very uncomfortable for us, as we were watching the story unfold in the news and we knew that we were helping to find someone's father or brother... We usually work on very old cases where there are unlikely to be any close relatives still living."

One such cold case that Lawley, Trick and colleagues have been working on relates to the disappearance of 16-year-old Emma Alice Smith in 1926. The teenager was last seen setting off on her bicycle from her home in Waldron, East Sussex, to catch a train to work. She was never seen again and, after an initial search failed to find her or her bicycle, it was assumed she had run away.

Police reopened the case in February 2009, when a deathbed confession from 1953 came to light. The dying man had confessed to a relative that he had murdered the young girl and dumped her body and the bicycle in a local pond. The confession remained a secret for more than 50 years.

"Over time the landscape changes and features that were there in 1926 may not be there now. The pond may have been filled in, for example," says Lawley. "But we have historic maps, plus the technology and expertise to look at where the pond might have been."

BGS has been creating geological maps for 175 years. These began as beautifully hand-painted watercolours, then printed and more recently web-based versions. The latest maps are now available on a smart-phone app - iGeology. As the technology has evolved, so have the ways in which geological mapping can be applied.

BGS worked with virtual-reality specialists Virtalis, to develop software that allows the scientists to investigate landscapes from the comfort of their offices. The scientists can overlay geochemical maps, road networks and the like over aerial photographs covering the whole of the UK. They view these in a 'visualisation suite', where 3D images can be projected from floor to ceiling.

"It is an incredibly powerful virtual reconnaissance tool," says Trick. "Think Google Earth, flying around in a helicopter wearing 3D glasses. Your avatar can walk around in a virtual world, fly through landscapes and also dive underground where it can find concealed caverns or deep-water lakes."

The GeoVisionary maps can test for 'line of sight' visibility on the surface, so they can look for potential witnesses to crime and confirm what they might have seen, depending on their position. They can also find deep lakes or reclaimed quarries and, by overlaying the maps with accessibility or slope-analysis tests, they can work out if they are deep enough to conceal a vehicle - or a body and a bicycle.

Lawley comments: "We can visit an area in virtual reality, as if we were under an invisibility cloak, and no one will ever know we've been there. It's an amazing piece of technology." This same technology may help to lay Emma Alice Smith to rest.

"Our work with the police helps the public good and goes hand in hand with our bread-and-butter work," says Trick. "We don't do it every day, so when we're called in to work on a case it's exciting and novel for the scientists. We can find small pieces of evidence which, when added to existing knowledge, help to build the bigger picture. It's very rewarding to know that our science can find concealed objects or place a perpetrator at a crime scene."

One thing is for sure - the technology and methods used in forensic geology have come a long way since 1887, when fictional detective Sherlock Holmes identified the origins of the mud on his fellow travellers' shoes.

Professor Mark Harrison MBE was until recently national search adviser for homicide, missing persons and mass fatality disasters for the UK police. He now leads a division of the Australian Federal Police.

Julian Trick and Russell Lawley are geoscientists based at BGS Keyworth, Nottingham.