Alternate light sources, a much needed tool for CSIs
Over many decades, visible light sources were used during most searches of crime scenes. Although some forensic investigators would occasionally use ultraviolet (UV Black Light) to examine for crime scene evidence, white light was the mainstay.
Furthermore, 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 fibers, bruises, bite marks, wound patterns, shoe and foot imprints, gun shot residues, drug traces, questioned
Secondly, what is ALS crime scene? Examination of crime scenes using monochromatic light sources (light of one specific wavelength) can assist in locating and identifying potential evidence. Devices providing monochromatic light at specific wavelengths are referred to as Alternate Light Source (ALS).
Also know, how is UV light used in forensic testing?
Ultraviolet (UV) light technologies are used for multiple purposes in forensic investigations, including authenticating paintings and other fine art, authenticating signatures, analyzing questioned documents , illuminating latent fingerprints at crime scenes and trace evidence on clothing, analyzing ink stains, and
How do you take fingerprints with glass?
Fingerprints on glass (windows, drinking glasses, etc.) can be photographed by placing a white card behind the glass and using a low oblique angle of light. They can also be photographed by using transmitted (back) lighting by positioning a diffused light source behind the glass.
12 Related Question Answers Found
What is an alternative light source?
Alternate Light Sources. Alternate Light Sources are typically used in crime scene investigation to identify many forms of evidence. Physiological fluids (semen, urine, and saliva) can be identified through their natural fluorescent properties utilizing UV light.
How do forensic scientists use light to collect evidence?
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.
Is luminol real?
Luminol is a white-to-pale-yellow crystalline solid that is soluble in most polar organic solvents, but insoluble in water. Forensic investigators use luminol to detect trace amounts of blood at crime scenes, as it reacts with the iron in hemoglobin.
What body fluids glow under black light?
Biological Fluids Beneath a black light, blood turns black, unless sprayed with luminol which gives it a blue-glow. Saliva, semen and urine also glow when hit with a black light. Most biological fluids contain fluorescent molecules to help them glow.
What is a video spectral comparator?
Video Spectral Comparator. EUROFINS FORENSIC SERVICES use a VSC 2000HR (Video Spectral Comparator) for the specialised lighting examination of documents. This instrument is capable of viewing and recording the response of documents/inks when exposed to light of various wavelengths.
Where do ultraviolet wavelengths fall?
What is Ultraviolet Light? UV (Ultraviolet) Light refers to the region of the electromagnetic spectrum between visible light and X-rays, with a wavelength falling between 400 and 10 nanometers.
What is alternative light photography?
Alternative light source photography. Infrared photography is used to enhance difficult to see blood on dark and patterned clothing, and tattoos post-mortem difficult to see due to decomposition, lividity and burning. We look at which light source is best for different situations and needs.
Why do police use UV light?
Police can use UV light to prevent and detect crime. Money is something that we don’t want to be copied or forged, so banks protect it by putting markings on it that are invisible under normal light, but can be seen under UV light. We can also use UV to protect things we don’t want to get stolen with invisible labels.
How does UV light work?
The energy from the ultraviolet light is absorbed by the fluorescent coating inside the fluorescent lamp and re-emitted as visible light.” Similar tubes without the same fluorescent coating emit UV light that can be used to disinfect surfaces, since the ionizing effects of UV radiation can kill most bacteria.
Is pollen an example of trace evidence?
Fibers, hair, soil, wood, gunshot residue and pollen are only a few examples of trace evidence that may be transferred between people, objects or the environment during a crime. Investigators can potentially link a suspect and a victim to a mutual location through trace evidence.
How is a video spectral comparator VSC used by a document examiner?
The Video Spectral Comparator (VSC) uses filters to vary the light bombarding the document. The document is viewed through a camera and computer monitor. As the wavelength of the light is varied, the picture changes.
What is ALS light?
The Advanced Light Source (ALS) is a specialized particle accelerator that generates bright beams of x-ray light for scientific research. Electron bunches travel at nearly the speed of light in a circular path, emitting ultraviolet and x-ray light in the process.