The public’s obsession with true crime stories has had a resurgence recently, fuelled by cult documentaries such as Making a Murderer and a host of crime podcasts. A common theme in these stories is how advances in forensics are helping police to crack difficult cases or shed new light on past crimes.
Fingerprint and DNA analysis are now seen as everyday tools used to catch and convict criminals and to exonerate suspects. Alongside these established methods, police and forensics investigators are increasingly using 3D scanning techniques developed in the engineering and academic worlds to bring fresh insights to criminal investigations.
Researchers at Warwick Manufacturing Group (WMG), based at Warwick University, are well known for work in the automotive and aerospace industries. But in recent years they have been applying their 3D scanning techniques to criminal forensics as well.
Professor Mark Williams at WMG says: “There are a lot of economic pressures within the public sector so to be able to access state-of-the-art equipment, such as high-resolution micro X-ray computer tomography scanners, in a collaborative research environment is quite novel.”
These metrology-grade systems can cost upwards of £1 million and are used to generate 3D images at a micron scale. WMG typically uses them for the characterisation of materials to create the next generation of carbon-fibre and composite materials. Williams explains that the team at WMG has also been using these techniques to effectively “zoom in” to areas in bones found at crime scenes that are deemed suspicious or in areas that pathologists have identified as potential causes of death.
A collaboration led by West Midlands police has seen the WMG use these 3D imaging techniques, along with 3D printing and 3D visualisations, to provide key evidence to solve some prominent murder cases. This has included the highly publicised investigation of the murder of Michael Spalding. Most of his remains were found dumped in two suitcases in a canal in Smethwick in 2014.
Small fragments of bone were found in the garden of Lorenzo Simon, who was subsequently convicted of the murder. Neighbours had seen Simon burning a bonfire in an oil drum in his garden following Spalding’s disappearance. Found among debris from the oil drum, the bone was so badly burned that Williams says traditional forensic methods were unable to analyse it. But, using the 3D scanning technology which provides image resolution down to 17,000th of a millimetre, the researchers were able to show a perfect jigsaw fit between the charred bone and a severed limb found in one of the suitcases.
Nine pieces of bone were repeatedly X-rayed at a range of angles with the many thousands of images collated using software to produce 3D ultrascans. They were then displayed on a virtual-reality 3D video wall, allowing detectives, forensics experts and crown prosecutors to examine the digital images in unprecedented detail. This helped officers to match the serrated edge of the saw used to dismember the body to the indents inflicted with a blade width of 1.4mm. WMG also 3D printed replicas of the bone to further visualise the injuries.
Williams says that the combination of micro computerised tomography scanning, 3D printing and 3D virtual reality was a first for the UK. The evidence linked Simon to the crime and he was sentenced to at least 19 years in prison.
These technologies are helping WMG to create 3D models and characterise “micro injuries” that normal computer tomography scanning or the human eye could miss, says Williams. This is proving particularly helpful in strangulation cases. He says the technology is “redefining how pathologists understand these kind of injuries”.
The 3D digital images are more sanitised than crime scene photo evidence, which owing to its graphic nature may be blocked by the defence, but can still be used to build up a more detailed understanding of the crime for juries.
Importantly, though, Williams says the techniques are not being used to catch more people but rather to get to the truth. “Police may end up wasting a lot of time, money and effort to carry out an investigation when using techniques like this early on could establish it wasn’t a crime, which saves the family and the police a lot of pain and effort,” he says.
As the techniques being used have been adopted for many years by the aerospace industry, Williams stresses that the certification and metrology standards are rigorous and traceable. Yet “winning over the hearts and minds” of a conservative justice system can be difficult. So far 3D printed evidence from WMG has not made it into the courts.
This is a problem also acknowledged by archaeology researchers at Staffordshire University who are working to combine 3D scans and virtual-reality headsets to bring accurate virtual representations of crime scenes into police stations and the courts.
Virtual-reality headsets are relatively costly. This problem could be overcome by giving one juror a headset while the scene they can see is projected on a screen for the rest of the court to view. However, Kevin Colls, archaeological project manager at Staffordshire University, says the biggest challenge is in convincing the courts of the merits of the technology. He says this will only come by carrying out demonstrations to lawyers. Fortunately the university is well placed to do so through its links from its law school to the crown court in Stoke-on-Trent.
The project, led by Dr Caroline Sturdy Colls, has grown out of many years of expertise that the archaeology department has built up in creating 3D environments for dig sites and in using laser scanning in forensic archaeology. This has seen researchers work with police forces to search for items that perpetrators have buried, from drugs and weapons to murder victims.
In what the researchers believe is a first, the project seeks to use photogrammetry (high-resolution digital photography that can be used to create virtual 3D environments) with virtual reality to demonstrate data from crime scenes in an immediate and immersive way.
While laser scanning technology is widely used in certain types of police cases, such as for analysing vehicle collisions, Colls explains that it has tended to be used less frequently in projects where forensic archaeologists get involved, such as in the analysis of burial sites of murder victims.
Current laser scanning technology that is used to document crime scenes is costly and time consuming. The area must be cleared of people while the scanner rotates and shoots lasers in multiple directions to create a point cloud, or 3D map, of the site. The scanner will also take photographs at various angles and lay them over the point cloud to create a virtual-reality environment. In contrast, photogrammetry requires a person to take multiple digital photos of the site while the 3D environment can be created using software off-site. This is less costly and means the user can vacate the crime scene more quickly.
Colls says: “Bringing that data into a virtual-reality environment makes it easier for police, courtroom staff or juries to put themselves into that crime scene and appreciate space and angles and see evidence as it was when police arrived. It will make crime scenes a lot easier to explain to people.”
The university will continue to develop the technique, in particular for use in documenting outdoor crime scenes.
Colls hopes that one day creating 3D virtual environments of crime scenes using photogrammetry will be standard practice. The resulting data could be kept on file and re-examined if new evidence on a case comes to light. “There is nothing worse than a new piece of information coming to light on a case from 15 years ago and finding that the case record is incomplete or inaccurate” says Colls.
However, more research still needs to be done in tandem with the university’s gaming research department to make the software and virtual-reality experience more user friendly and less expensive.
Cutting costs for police forces has been a driver behind the development of software for footprint analysis by Professor Matthew Bennett and Dr Marcin Budka from Bournemouth University. Funded by the Natural Environment Research Council, they have brought together around a decade’s worth of research and software development in the field of geological analysis of ancient footprints, which has ranged from “dinosaurs to humans”.
While Bennett is a geologist and Budka a data scientist, they were keen to apply their expertise to an area that would be of “societal use”. In July they launched their free, open-source software, DigTrace, that can be used to create detailed 3D images of footprints from crime scenes using photogrammetry.
Bennett says that, while footprint or footwear evidence has tended to be neglected in modern crime scene investigations, owing in part to advances in technology for fingerprints or DNA evidence, it has now become “a Cinderella of the forensic world”.
Currently police tend to rely on 2D photographs, or in important cases casts are made from dental stone. The DigTrace software should make capturing and sharing data less time consuming and costly. “Think about trying to share a plaster cast between officers in different parts of the country, whereas a digital file can be emailed in seconds,” says Bennett.
The value of 3D footwear analysis is as much in intelligence gathering as it is in criminal convictions. Bennett gives the example of capturing footprints from verges near car parks that have a reputation for criminal activity. If there is a commonality found between those footprints it will tell police that they are looking for just one group of people.
The software’s other advantage is that it has an in-built “custody chain”. This means it saves a zipped archive of the file during every processing step so that a third party would be able to interrogate the entire process to determine its validity – useful if ever used as evidence in a court.
The project, which has been supported by the Home Office and the National Crime Agency, has gained a great deal of interest from UK police, and DigTrace already has users lined up.
Bennett says he and Budka will continue to improve the stability and speed of the technology. They will also explore, with IT development company Base, the potential of using a remotely accessible server for police to access and run the software. Bennett says that the IT infrastructure in many police forces leaves a lot to be desired. The goal, however, is to expand the user base to police in the US over the next six months.
These are only a handful of the latest developments in 3D crime scene technology, and many more will follow. But what seems most evident is the passion that the academics and engineers display for pushing forward these technologies into the realm of forensics.
Williams at WMG says: “My day job is engineering and working with major aerospace and automotive companies. We have ported those systems across to a really novel and innovative area for real societal impact. It shows just how exciting the engineering profession is.
“It’s not just smashing rivets – it’s a really exciting field to be in, and you’re only restricted by your imagination.”