The science of finding buried bodies
Ian Brady, who tortured and killed five children in the UK in the 1960s with his accomplice Myra Hindley, died in prison on May 15. Jailed in 1966, Brady buried four of his victims in shallow graves on Saddleworth Moor outside Manchester – and the remains have since been found. Sadly, the body of one his victims, Keith Bennett, however, is still missing.
Brady's death has left Bennett's family feeling like the final chance to find his remains has been lost. The police, however, insist that the search will go on. But how do you go about finding a lost body after so many years?
UK Home Office statistics show that around 2,000 of the 200,000 people who are reported missing each year are still not found after 12 months. Some want to start a new life, but an unknown number become victims of crime. Some are murdered. Most of these cases are solved fairly rapidly, but some – so-called cold cases – are harder to crack.
Luckily, science can help. In many homicide cases, bodies end up getting buried in the ground. There are various scientific methods that can help locate such victims, with one of the most important being to identify variations in the surface, such as depressions or small hills, which could indicate that a body has been buried underneath. Search teams can also use specialist "cadaver dogs" to sniff for remains or geophysical methods to scan identified areas. The latter include ground penetrating radar, which uses radar pulses to image the subsurface.
We recently published a review which set out best practice when it comes to finding bodies on land. We discovered that a phased approach usually yields the best results. This involves starting with analysis of large-scale satellite data to locate potential burial areas – for example where soil has been recently disturbed. You then proceed with initial site investigations, looking at suspect areas to find out the soil type and other environmental data. The last stage involves carrying out focused site searches and digging.
Control studies with animal and human bodies
But despite this knowledge, the current detection rate of cold cases is low – perhaps only one in 100 cases are successful. As each case is unique, control studies using purpose-built clandestine graves are helping us further work out which detection techniques work best in which cases. In the UK, we currently use pigs as human analogues, although the US, Australia and, since January, the Netherlands, use donated human cadavers.
The approach needed will change as a body decomposes (see figure below) – with the local soil type, burial style and the types of rock in the ground also being important variables. A 50-year-old body buried in a shallow grave in the moors may be relatively intact in wet peatland, whereas a recently buried body in dry sand will rapidly decay.
Ground penetrating radar is best to locate bodies that have been wrapped in something (wrapping provides a good reflective surface). In other cases, where the body is still decomposing, fluids such as blood from the cadaver can be detected by machines that measure electrical resistivity – how strongly a material opposes the flow of an electric current. In a recent study, we showed that conductivity in grave soil water rapidly increases up to two years after burial – data which we can use to estimate the time since death.
Control studies can only go as far back in time as experiments last, so researchers have also been looking at real graves that are much older to assist with more ancient missing persons cases.
Graveyards and cemeteries are an obvious choice for this. These can be geophysically surveyed, most commonly with ground penetrating radar and electrical resistivity to look for bodies buried without a grave stone. These can be exhumed, both for research purposes and to confirm the identity of the remains. We did this recently when new church community halls were being built on old graveyards. Exhumation regulations differ across the world, but in the UK you are allowed to do this if burials are over 100 years old.
An issue with this, however, is that graveyard burials are in coffins, often along with preservatives. Few accidental burials or homicide graves use coffins or chemicals. Nonetheless, ongoing geophysical research of graveyard burials is extending our knowledge of how long bodies are detectable for. This can certainly feed into cold case searches.
This kind of research has also improved our understanding of how well different survey methods work in different environments. For example, electrical resistivity surveys tend to work best in clay-rich soils whereas radar is best in sandy soils. We've also learned that gravestones are often not exactly in the correct position, and that graves containing many bodies are often not vertically aligned. This may occur due to coffins subsiding in soft ground, or in more extreme examples, due to "coffin slip", where in inclined ground, burials move down the slope over time.
Clearly more research needs to be done to improve detection rates of cold cases. In fact, the key is to combine collaborative academic control studies with input from search practitioners and experts. Advances in technology – such as drones that can help locate surveys in real time and more sensitive geophysical devices – are also allowing us to integrate both simple observations and advanced geophysical searches into one system.
There's certainly good reason to believe that Bennett was also buried somewhere on the moor. Initial searches, mainly using police manpower and volunteers looking for physical signs of ground disturbance, were unsuccessful. Many other methods have since been used, including specialist search dogs and metal detectors (should there be metal in Keith's clothing). Soil sampling and other tests have also been used to look for decomposition of fluids, but it is probably too late for this now. Ground penetrating radar has also been used to search for a skeleton.
However, these methods are time consuming and only a relatively small area can be surveyed each time. But, as long we continue looking – and use the latest technology and research to inform the search – there is every chance that we could one day find Bennett's body.