Tag Archive for: luminol

When Luminol Isn’t Quite Enough, Amplify It! Here’s How It’s Done …

Any writer, reader, and fan of mysteries, thrillers, suspense, and other books and television shows and film that involves crime scene investigation, will most likely have heard of Luminol, the chemical that causes chemiluminescence.

Chemiluminescence, the vivid bluish glow we’ve seen on countless crime shows, occurs when Luminol contacts an oxidizing agent such as the hemoglobin found in blood. Other agents can cause a similar reaction (copper, bleach, etc.), but it is blood that causes the most vivid glow. And it is this reaction that is of particular interest both real and fictional investigators.

Even bloody footprints reveal themselves when exposed to luminol.

Sirchie, the world leader in crime scene investigation technology and products, describes Luminol as:

“Luminol is a chemiluminescent substance that can be used as a presumptive test for the presence of blood. Making use of the peroxidaselike activity of the heme portion of hemoglobin, Luminol produces a bluish-white light that can be viewed in total darkness. Invisible blood stains react with the Luminol reagent by luminescing—darkness is essential. It can also be photographed or videotaped with the aid of the SIRCHIE® KRIMESITE™ IMAGER. A very useful test for searching large areas for blood especially if the area has been cleaned up. Sensitivity:1:100,000.”

Sirchie’s LUMINOL8 Contents:
2- LUMINOL 8B bottles of solution, 8 oz. each
2- LUMINOL 8A packets of dry chemicals, Net. Wt. 14.5 gms
2- Spray Head Attachment

*Sirchie image

Blue Star

Sirchie’s BLUESTAR Forensic Kit “affords the Crime Scene Investigator a complete tool to determine the presence or absence of blood. The extreme sensitivity of BLUESTAR allows the detection of bloodstains down to 1:10,000 dilutions, including minute traces that have been washed off, with or without detergent. And unlike other blood reagents, total darkness is not required. With practice, it’s unlikely to get confused between blood and false positives as the luminescence is different in color, intensity and duration. Subsequent DNA Typing and ABO Typing is possible because BLUESTAR does not alter the DNA in suspect blood stains.” ~ Sirchie

*Above image ~ Sirchie

Luminol is a presumptive test, not a confirmatory test.

 

 

 

 

 

 

Luminol presents challenges, such as its potential to destroy DNA evidence when contacted, and its glow lasts for just mere seconds. Detectives must be quick with their photography skills!

Therefore, BGU Prof. Alina Karabchevsky, head of BGU’s Light-on-a-Chip Group, a member of the BGU Unit of Electro-Optical Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, came up with a fantastic new idea … a device/chip that combines the use of luminol with gold or silver nanospheres.

Simply put, Dr. Karabchevsky invented a microfluidic chip that not only greatly increases the chemiluminescence intensity of luminol, but also extends its glow time. To sweeten the pot, the chip enables the detection of much smaller blood samples found at potential crime scenes.

“The method developed by BGU researchers will enable development of future detectors with improved sensitivity. We are currently looking for partners for further developing this promising patented invention,” said Netta Cohen, CEO, BGN Technologies.

What is a microfluidic chip?

Easy answer – a device (chip) that enables very small amount of liquid to be processed or visualized.

 

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Fingerprinting: A Journey From J-N

Especially for you, a J-N guide to fingerprinting … and more.

J.

JFI – Journal of Forensic Identification.

JFS – Journal of Forensic Sciences.

Joint – Hinged area where two bones are joined together.

K.

Keratinocyte – The major cell found in the epidermis.

Keratins – Highly insoluble fibrous proteins found in skin-related structures such as hair, wool, hooves and horns, claws, beaks, and even feathers.

L.

Latent Print – Friction ridge detail (fingerprint) that is not readily seen by the naked eye.

Law of Biological Uniqueness– Scientific Law stating that all items in nature are unique.

Leuco Rhodamine 6G – Reagent that reacts with the heme moiety of the hemoglobin of red cells in blood. It’s used to enhance and visualize fingerprints left in blood.

Leucocrystal Violet – A colorless form of gentian violet used to stain blood residue on both porous and nonporous items.

Lift– An adhesive or other vehicle used to transfer a friction ridge imprint (a fingerprint) from a surface.

Lights Out – Computer process where the AFIS computer automatically obtains friction skin features, searches the AFIS system, and presents an identification or exclusion based on a predermined score. No human is involved in this process.

Liquid Nitrogen – In its liquid state (-195 degree C), liquid nitrogen is ideal for the separation of adhesive surfaces.

Liqui-drox – A fluorescent yellow solution used to develop prints on both sides of dark-colored adhesive tapes.

Locard’s Principle of Exchange – Edmond Locard’s Principle of Exchange states that when any two objects come into contact, there is always transference of material from each object onto the other. (People entering a crime scene both leave and take away evidence, in some form).

Loupe – A small magnifying glass used in the identification and comparison of fingerprints.

Luminol – Chemical that glows with a bluish tint when it comes into contact with blood. it can detect blood at 1 part per million. It’s so sensitive, in fact, that one drop of blood within a container of 999,999 drops of water, will cause luminol to glow.

M.

MC’s – Major Case Prints.

MMD – Multimetal Deposition, a two step process using a colloidal gold and a physical developer solution to enhance latent prints.

5-MTN – Methylthioninhydrin, a reagent that reacts with amino acids to develop prints on porous items.

Medial Interphalangeal Flexion Crease – The middle crease on a finger.

Metacarpo-phalangeal Crease – Creases where the fingers meet the palm.

Microburst Method – Developed by the FBI, this method of developing prints is designed to expose a nonporous item to a large amount of Cyanoacrylate (Superglue) fumes for a small amount of time. The Superglue is positioned into a chamber heated to temperatures above 300 degrees. The item to be printed is then placed in the chamber for 30-45 seconds.

Minutiae – Small details.

Molybdenum Disulfide – Chemical used to prepare Small Particle Reagent (SPR). SPR is a means to develop latent fingermarks on wet, non-porous surfaces such as glass, plastic, metals and even the sticky sides of tape.

N.

NCFS – National Commission on Forensic Science.

NCIC – National Crime Information Center. To learn more about NCIC, click here.

NFB – National Fingerprint Board of England and Wales.

NV – Abbreviation for “No Value,” meaning a print has no value for identification purposes.

Stay tuned for exciting Writers’ Police Academy news. In the meantime, space is available so please hurry. Sign up today. This year is absolutely incredible!!

 

 

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