foster+freeman BLOG
Why use a forensic light source?
Why would we use a forensic light source when searching for evidence at a crime scene rather than just using our eyes or a normal torch?
Our market-leading Crime-lite ranges offer Infrared, Visible and Ultraviolet multispectral search tools, allowing us to detect more evidence.
Read on as we answer the question of why a forensic light source should be used when searching for evidence. We will look at the theory behind light, explain the forensic spectrum, and consider what we could potentially find when using a forensic light source.
Participants of the forensic escape room trying to connect the dots
In August of last year, we ran our inaugural Forensic escape room at the 107th IAI Educational Conference. Our on-site escape room challenges participants to utilise the latest forensic technology to identify the perpetrator of a diabolical murder before the clock runs out! Will they be able to connect the dots or will the killer evade justice?
The escape room focused on the use of forensic light sources to reveal clues, find the evidence and solve a murder case. It showed attendees at the conference how to use forensic light sources to reveal hidden evidence.
You can find more information on the conference here:
IAI Conference 2023
Key Products
Crime-lite Range
With the Crime-lite range of forensic light sources, foster+freeman has pioneered high-intensity LED illumination for the search, detection, and examination of forensic evidence both at the crime scene and in the forensic laboratory.
The Crime-lite range of light sources is synonymous with the scene of crime search and detection of evidence. Crime-lites are known for their unrivalled build quality with high-intensity LEDs specifically selected for wavelength accuracy. Never wavering Crime-lites are designed to give you 100% output power even when the battery is running low.
Laboratory Light Sources
In addition to handheld Crime-lites, we also manufacture laboratory-based forensic light sources. Our flagship product in this area is the Crime-lite ML PRO. The Crime-lite ML PRO is the first in a new generation of evidence screening tools built to meet the demands of busy forensic laboratories tasked with processing large quantities of evidence.
With fully integrated UV-Vis-IR illumination and an ‘intelligent optics’ imaging system, the ML PRO can mark up evidence, detect the presence of bodily fluids, and locate minute fragments of trace evidence.
Examinations are conducted using the system’s 10″ touchscreen display, which can be displayed in high resolution via an attached 32” monitor. Pre-set examinations and automatic filter selection make the system quick and easy to use.
Background
Forensic Light Theory
When searching for evidence at a scene, we must use the full forensic spectrum to reveal the greatest evidence. These are wavelengths from ultraviolet, visible light and infrared light sources. A forensic light source will increase the evidence detected and increase the efficiency of the crime scene and laboratory examinations. With today’s LED technology, we can use high-intensity LEDS, with the LEDs employed in the Crime-lites high-intensity LEDs, each hand-picked for brightness and wavelength accuracy, ensuring consistent performance and effectiveness.
Light is part of the electromagnetic spectrum, a collection of waves. Some parts of this spectrum are termed as “visible light”. Electromagnetic radiation with a wavelength between 380 nm and 760 nm is detected by the human eye and perceived as visible light. As the full spectrum of visible light travels through a prism, the wavelengths separate into the colours of the rainbow because each colour is a different wavelength. Violet has the shortest wavelength, at around 380 nanometers, and red has the longest wavelength, at around 700 nanometers. There are regions outside of these wavelengths, such as ultraviolet and infrared, which we term non-visible light. The Crime-lites can search for evidence along this full spectrum of light.
There are different ways a piece of evidence or material interacts with a forensic light source, depending on the wavelength used. This can include fluorescence, where material absorbs one wavelength and emits another (often called Stokes shift effect). Another way is absorption, where material retains particular wavelengths and then reflection; this is where the item returns the same light and doesn’t get absorbed into the item. Different types of evidence will absorb different wavelengths of light emitted from your Crime-lite and produce fluorescence that can be viewed; we can use goggles or filters to block out the emitted light, which is not being absorbed to view the fluorescent emissions. Crime-lite PRO-VISION viewing goggles are specifically designed for this use, enabling the user to quickly and efficiently switch between filtered googles without having to remove the goggles themselves
What types of evidence can we detect with a forensic light source?
Gloucestershire Constabulary
Semen, blood and fingerprints under the spotlight with new crime-scene tech
- Gloucestershire Constabulary is the first in the south-west to own a state-of-the-art forensics device to aid investigations.
- The device allows investigators to search, detect and capture vital evidence from crime scenes using one versatile device.
Gloucestershire Constabulary’s forensics team is the first in the Southwest to own a groundbreaking piece of technology that will allow investigators to secure better evidence from crime scenes in the county.
The new Crime-lite AUTO is described as ‘forensic imaging technology, combined with powerful multi-spectral illumination’, which, in basic terms, means local forensics teams can now use just one portable unit to search, detect, and capture evidence on site. Previously, teams would need multiple light sources and cameras to complete this job, with some evidence types undetectable without access to this new technology.
Chris Allen is Head of Forensic Services at Gloucestershire Constabulary: “In a modern, complex crime scene, having access to the latest and best technology not only saves processing time but produces better results and increases the ability to bring offenders to justice.
“This new equipment is at the leading edge of enhanced search systems available to the police and will undoubtedly be put to great use by Gloucestershire’s forensic investigators.”
The Science Museum
Semen, blood and fingerprints under the spotlight with new crime-scene tech
The Science Museum London’s Who am I? gallery displays real-life forensic cases that need to be solved. This equipment would have been used by a team of forensic scientists who worked with the metropolitan police to solve the crime, using the latest DNA profiling technology and forensic science techniques, particularly a light source examination of the scene and objects.
“Looking back over the centuries, how many crimes committed back then would have reached a different conclusion if they occurred today using modern science and technology? Advances in Forensic Science means that crime-scene evidence can be accurately gathered and examined, from collecting DNA and fingerprints to gunpowder residue from armed robbery, kidnap…”
One of the parts of the display that displays the tools used to solve these cases displays a range of Crime-lites used at the scene and in the laboratory to detect body fluids.
Crime-Lite- A Forensic’s handiest tool?
- Can you think of any infamous crimes that would’ve benefitted from a ‘Crime-lite’ or DNA profiling to solve the case?
- Can we rely on evidence collected in this way? Is it always 100% accurate?
- What could contaminate evidence? What preventative causes do you think police officers on a crime scene take to ensure they don’t disturb any evidence?
The World’s End Murders
Cold Case solved after 40 years thanks to Crime-lite technology.
On the evening of 15th of October 1977, two seventeen-year-old girls named Christine Eadie and Helen Scott, joined by two friends, Jaqueline and Toni, had been on a pub crawl. They walked into the World’s End pub in Edinburgh Old Town on the Highstreet in the Royal Mile just before the last orders. Christine and Helen decided not to join Jaqueline and Toni at a house party but called it a night and headed home. They were last seen leaving the World’s End pub. The next day, Christine’s body was found in Gosford Bay, East Lothian, by Ramblers. Later on, Helen’s body was discovered six miles away from Christine’s in a corn stubble field. Both girls had been beaten, gagged, tied up, raped, and strangled. No attempt had been made to conceal their bodies.
This discovery started a high-scale high-profile murder investigation, in late 1977 Lothian and borders police conducted a criminal investigation, collating a list of over 500 suspects and taking over 13,000 statements from members of the public. Despite this exhaustive list and search for suspects, they could not identify a culprit. The case naturally gained widespread media interest at the time, and the police used photo booth pictures of the two girls for appeals for information at the time.
The media reported that several witnesses had told police they had seen the two girls sitting near a public telephone in the bar talking to two men. However, neither of these two men was ever identified. Speculation that the killings had been the work of two men was heightened when it was revealed that the knots used to tie the girls’ hands behind their backs were of different types.
In 1977, it was old-fashioned police work; they didn’t have advanced DNA profiling or high-powered forensic light sources; in 1978, officers were forced to scale down the investigation with the murderer still at large.
Eventually, a breakthrough would occur thanks to the Crime-lite light sources. When shone on the victim’s jacket or the binding that held their hand together, potentially invaluable DNA evidence shone out like a star in the night sky, directing investigators to give a second look to a piece of evidence they would never have given a second thought to in the 1970s. In this case, it reveal evidence that would finally put the case to rest 40 years later. It would show Angus Sinclair and brother-in-law Gordon Hamilton’s DNA was all over the evidence. Used for the first time ever in a Scottish case, A large garment – such as Helen’s coat – offered many possible points of DNA contact. Crime-Lite suddenly provided a devastatingly accurate guide to where to take their samples. One major significant find was that of Hamilton’s DNA within a fold of Helen’s tights.
“Without Crime-Lite, there would have been no trial two, ” says Lord Advocate Frank Mulholland. He was so impressed with the equipment that he made representations to senior forensic unit management to have it introduced to the Scottish labs.
Crime-lite AUTO Ground Truth Studies
Grounded in truth
When it comes to using a light source. How do you know if or how much evidence is being missed?
Foster+freeman invested a huge amount of time and research into this very question. Research has always shown that to detect the greatest amount of evidence; examiners should always employ a wide range of wavelengths from UV to IR when searching for evidence.
When Foster+Freeman began developing our latest range of Crime-lite products, we decided to explore ways to scientifically verify the optimum search and detection settings required to reveal the most evidence.
We conducted ground truth studies to determine the optimum search and detection settings for various evidence types. We decided to start with body fluids due to their frequency of occurrence at crime scenes, difficulty detecting and observing, and value as a source of vital DNA evidence.
Presumptive tests are necessary for all body fluid identification before DNA analysis. This takes time, costs money, and often involves wetting & drying of the evidence, leading to a loss of stain pattern and potential loss of valuable DNA. In 2020/21, 242,117 individual new profile records were added to the national DNA database, so you can imagine the amount of time, energy, and money spent daily on identification, collection and recording of DNA found at a crime scene.
By understanding how body fluids and fabrics interact with high-intensity illumination, we can improve our ability to detect these invaluable sources of evidence at the crime scene and during laboratory examinations.
Why can we detect valuable evidence on one garment but not another?
The myriad of dyes, pigments, material types, and surface coatings used during manufacturing play a significant role in visualising the forensic trace of interest.
To this end, Foster+Freeman has spent the last two years developing a dataset of approximately 19,000 images of body fluids deposited across a representative range of fabrics.
Multispectral analysis of each sample has facilitated the development of a gold-standard, industry-leading Product Verification Library to support both product utilisation and end-user verification and validation.
We put this dataset to good use with this new dataset of 19,000 images of body fluids and how they interact with the fabric, light wavelength and filter. We have implemented this knowledge into the Crime-lite AUTO. Within the Crime-lite AUTO, preset examination modes are available, giving you the best light and filter combination for the evidence you are searching for and the material it is deposited on. Ground truth data empirically backs up these preset examination modes and helps you detect more evidence.
Conclusion
In summary, there is always more evidence at a crime scene than can be visualized with the naked eye. Different illumination wavelengths are used to locate and examine a range of different types of forensic evidence. Examination of evidence beyond the visible spectrum may reveal more than fluorescence examination alone, and crime lights can increase the amount of evidence that is detected by supporting Multi-Spectral illumination across the entire spectrum.
To detect more evidence, it is imperative that you employ the use of a forensic light source when searching for evidence. Many pieces of evidence can be detected with a visual search or with a torch. However, to detect the hidden evidence we must do a full multi-spectral sweep of the crime scene with a forensic light source.
Forensic light sources are a very useful preliminary screening tool for the detection and examination of evidence. Furthermore, they can assist in directing examinations, as well as providing additional information that can be incorporated into an overall interpretation of the findings.
One main advantage of a forensic light source is that it is portable. A portable forensic light source can do a preliminary search on awkwardly shaped or heavy items of potential evidence, allowing the examiner to quickly and easily determine if further, more expensive, time-consuming, and rigorous testing is needed.
With new technology such as the Crime-lite AUTO on the market, It’s not hard to see why so many police forces worldwide are equipping their crime scene teams with the Crime-lite AUTO. Multi-spectral imaging, particularly in the non-visible parts of the spectrum, is a precious tool for the detection of a wide range of evidence types – and by combining all of the required elements – camera – lighting and filters into a single device, we can greatly reduce the time it takes to conduct a thorough investigation.
Forensic light sources are now an essential tool in the CSI’s kit, enabling the examiner to do a thorough and conclusive first sweep of a crime scene without disturbing or destroying evidence. Shining a light on areas of a crime scene that would never have been found before, illuminating valuable hidden evidence.
Learn More
Crime-lite® 82S PRO
Detect more evidence using Crime-lite 82S PRO light sources, a powerful upgrade to our best-in-class forensic search tools.
Used and trusted by law enforcement, military, and clinical forensic examiners worldwide, Crime-lite 82S light sources can be relied upon to provide the high-intensity narrow bandwidth illumination required to detect even the smallest traces of forensic evidence.
Now, the Crime-lite 82S PRO range builds upon that time-proven technology, providing CSIs and forensic examiners with the illumination they need to Detect More Evidence.
Crime-lite® AUTO
A Compact and Portable Solution for Multispectral Examination
RELATED WEBINAR
Crime-lite Forensic Light Sources – For the Detection and Examination of Body Fluids
This webinar will include comprehensive demonstrations of our latest range of high-intensity narrowband forensic light sources for the detection of body fluids including semen, saliva, sweat and vaginal fluids at the crime scene and in the laboratory. Watch Now