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Forensic Light Source Applications

The value that a forensic light source will bring to your department will be measured by the significant increase in the number of suspects apprehended and successfully prosecuted.

What is a Forensic Light Source?

A forensic light source is a crime scene investigator’s and lab technician’s tool for enhancing observation, photography and collection of evidence including latent fingerprints, body fluids, hair and fibres, bruises, bite marks, wound patterns, shoe and foot imprints, gun shot residues, drug traces, questioned documents, bone fragment detection, etc. It provides more sensitivity than traditional methods thus increasing the amount of evidence uncovered and the quality of the evidence photographed and collected.

A forensic light source is made up of a powerful lamp containing the ultra-violet, visible and infrared components of light. It then filters down the light into individual colour bands (wavelengths) that enhance the visualization of evidence by light interaction techniques including fluorescence (evidence glows), absorption (evidence darkens), and oblique lighting (small particle evidence revealed).

Utilizing forensic light source techniques allows the latent print to be detected with much more sensitivity (10-100 times more!) than the conventional method of black powder dusting and lifting.

Latent Fingerprint Detection

The primary application of a forensic light source is for enhancing the detection of latent fingerprints. The use of fluorescent enhancement processes that compliment a light source greatly increases the types of surfaces from which a latent fingerprint can be detected. Consider the difficulties of dusting and lifting a print off of the following surfaces: thin plastic bags, rigid duct tape, thin aluminium foil, heavily grained wood, concrete wall, brick, printed glossy magazine pages, paper products, etc. Using traditional methods, fingerprint evidence on these and other types of surfaces may go undetected or even dismissed because they could not be detected with enough detail. Forensic light source techniques have been successfully utilized for revealing latent prints on these and many other types of textured surfaces, backgrounds which mask ridge detail, fragile surfaces, and contaminated surfaces. Different colour bands (wavelengths) are required for processing different types of surfaces making a forensic light source with tuneable or multiple colour bands (wavelengths) a coveted tool for any crime scene investigator. In many cases the background surface will also glow under light source illumination. In these cases it is necessary to tune to a colour band (wavelength) of light that causes the print to glow and not the background. The quality and quantity of evidence revealed is proportional to the output power and the extent of colour tuneability of the light source. This ability is exclusive to a forensic light source, UV lights or Blue lights cannot offer this selectivity due to their limited number of colour bands (wavelengths) and low power.

Since fluorescent techniques are very sensitive, only trace amounts of fluorescent powder are required when dusting for prints at a crime scene . It therefore leaves the scene much cleaner than when using black powder.

BODY FLUIDS

Since body fluids like semen, saliva, and vaginal fluids are naturally fluorescent, the use of a light source offers a unique method for locating them. A crime scene investigator can narrow down the specific locations of stains for collection instead of testing entire, large pieces of evidence such as a mattress, a carpet, a sheet, an article of clothing, etc. The dried body fluids will actually glow under the light source illumination. Although the body fluids will fluoresce under an ordinary UV black light, many articles on which you would find them including clothing and sheets will also glow and deter their detection. It is therefore necessary to tune to visible colour bands (wavelengths) to eliminate the background interference. Considering you will be searching for body fluids on high profile, capital crime cases, the more body fluid evidence you can reveal the better. Again, the more powerful and more tuneable your light source, the more evidence you will uncover. Although blood does not glow in the visible range, it has a unique colour band (wavelength) under which the blood stain will darken to enhance its contrast by approximately 4 times. This is most effective in photographing blood prints because more of the detail of the blood print will be revealed by the enhanced contrast.

Many background surfaces glow under UV light and therefore a simple UV Black light will not yield the quality and the quantity of evidence that can be achieved with a tuneable or multiple colour band forensic light source.

HAIR & FIBRES

Two light illumination methods can be employed to locate hair and fibres with a forensic light source. First, oblique or parallel lighting of a surface such as a floor or carpet with a strong white light (the more powerful the better) will reveal small particles like hair and fibres for collection. Second, some hair and fibres will also glow under UV or visible light and will stand out strongly for collection. For the best chance of collecting the maximum number of hair and fibres at the crime scene, you need a powerful light source that offers strong White light illumination as well as strong UV and visible colour bands (wavelengths); all of which are available only in a forensic light source.

A blue filtered flash light is limited by a single blue colour band and even more severely by the limited power output of a flash light.

BRUISES / BITE MARKS / PATTERN WOUNDS

A tuneable or multiple colour band (wavelength) forensic light source reveal bruise and patterned wound details that are invisible under normal white light illumination. Details of a bruise pattern in a suspects palm can link a suspect to a weapon. Furthermore, details of a bruise on a victim, for instance, a bite mark or a shoe mark, can link a suspect to the victim. Multiple colour bands (wavelengths) are necessary because different colours penetrate to different depths within the skin and therefore depending on the depth of the bruise or wound you will need to vary the colour band (wavelength) of the instrument. Deep wounds may require infrared illumination to get enough skin penetration.

Only a forensic light source gives you the versatility of UV, visible, and IR colour bands for enhancing bruise or wound pattern detail.

QUESTIONED DOCUMENTS

Inks have different formulations, even within the same apparent colour type. A tuneable forensic light source can be used to identify slight variations in ink type by viewing ink responses as the colour of the light is tuned through the visible and infrared regions. Regardless of the skill of the forger, this examination would reveal that 2 different pens were used on the document.

WHY CHOOSE A SPEX CRIMESCOPE FORENSIC LIGHT SOURCE?

The SPEX Mini-CrimeScope 400 multiple colour band (wavelength) forensic light source and the SPEX CrimeScope CS-16 tuneable forensic light source offer the following advantages over other available forensic light sources:

MORE POWER: Both units offer considerably more power output than even the nearest competitor. The difference is visibly apparent and the advantage is clearly evident in the ability to look at fainter evidence with our units. The reason for the greater power is design. Both units take advantage of the latest in Liquid Light Guide technology as well as incorporate the highest quality optics.

MORE COLOUR BANDS: Both units offer more colour bands (wavelengths) than their competitors. The Mini-CrimeScope 400 offers wavelengths in multiples of 6 (6, 12, 18, etc.) with field interchangeable 6 position filter wheels. The CrimeScope CS-16 incorporates 24 wavelengths for the UV, Visible and the IR, our nearest competitor offers only 12 wavelengths. The CrimeScope also offers 15 positions for continuous tuneability, more than any other light source giving the highest overall intensity throughout the spectrum.

MORE USER FRIENDLY: The CrimeScope line of forensic slight sources are the only units that offer true ONE HAND OPERATION of colour band (wavelength) selection; the Mini-CrimeScope 400 with its patented 6 position thumbwheel at the working end of the light guide, and the CrimeScope CS-16 with its automated remote control at the working end of the light guide. These are the only units on the market which truly allow you to take advantage of the 2 meter light guides while processing hard to reach areas like the insides of vehicles. Additionally, ONE HAND OPERATION of the light source allows the other hand the opportunity to dust or collect for evidence.

FULLY UPGRADEABLE: The CrimeScope line of forensic light sources have the ability to be upgraded at any time in the future. If a new application was developed for the light sources, filters can be added to both units to cover that new application. This upgrade ability is cost effective, as you only need to purchase today what wavelengths you need and can afford, upgrades allow you to spread the cost of the unit over multiple budgets.

APPLICATION TARGETED DESIGN: The CrimeScope line was not designed overnight. It evolved from a test bed to a commercial product, to 2 distinct classes of light sources, and then finally to the State of the Art forensic instruments you see today. Each step of the way the designers worked with professionals in the forensics field from the federal, state, and local levels to find out what the community needed and wanted. The resulting CrimeScopes are the most versatile, most rugged and easiest to use of any light sources ever available. Because of their performance, SPEX has the most loyal users in the field, returning to us for more units when they expand their departments capabilities.

We are confident the Mini-CrimeScope 400 and the CrimeScope CS-16 are the best forensic light sources available, so sure that we encourage side by side demonstrations and trials with our competitor's units.

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Forensic Light Source Applications