Skip to main content

Uses of Mobile Application in Crime Scene Investigation

Applications of Infra-red (IR) Radiations in Questioned Document Examination


By,

Dr. Bhoopesh Kumar Sharma
Forensic Expert & Associate Professor
GET HELP FOR YOUR ANY ASSIGNMENT/ PROJECT/ RESEARCH PAPER/ TERM PAPER IN FORENSIC SCIENCE
www.globalforensicexpert.com

Dear Students,

In the last section, we have discussed the uses of UV rays in Questioned Document analysis, and now in this section, we will summarize the applications of Infra-red for questioned document examination.  

Infrared radiation (IR), is electromagnetic radiation (EMR) with longer wavelengths than visible light. It is therefore generally invisible to the human eye, although it can be felt as heat by humans. IR wavelengths extend at 700 nanometers (frequency 430 THz) from the nominal red edge of the visible spectrum to 1 millimeter (300 GHz). Most of the thermal radiation emitted by objects near room temperature is infrared.


UV-IR Spectrum

One of the most characteristic feature of IR rays is that, they are readily absorbed and converted in to the heat energy. Unlike, UV rays, it does not have any fluorescent effect and can not be viewed by the unaided eye. The basic source of IR radiation in forensic work is 1000 watt tungsten filament lamp. Various filters are needed to screen out all other light waves and to allow only IR rays to pass through.

Applications of Infrared in Questioned Document Examination:

1. Analysis of Inks: In any disputed or altered document, in which the use of two different types of inks is suspected, can easily be deciphered through infrared radiation. An example is given below in the image. This is due to the differences among the reflectivity of the ink used. One ink will be more reflective than the other under certain wavelengths of IR. Hence, one will be more darker and other will appear lighter. 

Source: http://www.forensicsciencesimplified.org/docs/why.html
Source: https://www.in.gov/isp/labs/2406.htm

2. Analysis of Obliterated Writings: Writings can be obliterated in number of ways. For instance, by using correction fluid and then over-writing, or by damaging the previous text and then over-writing or in any other such manner. One ink will be opaque and other will be transparent at certain wavelength. Therefore, by changing the wavelengths of IR radiation, it is possible to read the obliterated matter easily. 



Source: https://www.forensicdynamics.org/gallery/

3. Examination of Erasures: Small particles of the ink or pencil often linger in the outline when writing is erased mechanically. With an infrared radiation or infrared imaging, it may be possible to make the writing clear.

4. Charred Document Examination: The burnt document examination, sometimes is only possible through infrared photography, however, it depends upon the type of the ink used and the degree of burning. 

5. Cancellation Marks: After their first cancellation, postal stamps are often reused. The cancelation mark residues may not be visible duets the stamp's dark background. An infrared photograph may reveal the remains of previous marks of cancellation.

6. Water Damaged Documents: By photographing the water damaged documents with the aid of light transmitted by the blue-green infrared blocking filter, the residual ink in the paper fluoresced in the infrared and this can be recorded further to decipher the written matter. 

By,
Dr. Bhoopesh Kumar Sharma
Forensic Expert and Associate Professor
https://allaboutforensic.blogspot.com
www.globalforensicexpert.com

Comments

Post a comment

Popular posts from this blog

Crime Scene Search Methods

The Crime Scene is search for the physical evidences (visible or invisible). There are various types of search methods employed by the investigating officers and the forensic scientists at the scene of crime. The searching methods mainly depends on: Type of Crime (Rape, murder, burglary, theft, etc.) Nature of Crime (Homicide, suicide, or accident) Size of the crime scene (macroscopic or microscopic) Location of the crime scene (indoor, outdoor, combination of indoor or outdoor, or any remote area like underwater, desert, etc.) Complexity of the crime scene  Before deciding the search method, all the investigators and the forensic experts must follow the general guidelines (check list) to observe the crime scene after due recording: 1. Are the doors and windows locked or unlocked? Open or shut?  2. Are there signs of forced entry, such as tool marks or broken locks? 3. Is the house or the crime scene is in good order? If not, do

Introduction to Forensic Ballistics

By Dr. Bhoopesh Kumar Sharma Forensic Expert & Associate Professor Introduction to Ballistics: The term ballistics refers to the science of study of the action, motion and  behaviour  of a projectile during its flight in any given medium. The flight path of a bullet includes:  • Travel down the barrel  (Internal Ballistics), • Path through the air  (External Ballistics),  and  • Path through a target  (Terminal Ballistics) Forensic Ballistics: Is that branch of forensic science which deals with the examination of the firearm and related evidences encountered at the scene of crime in a shooting incident, and their linkage to the firearm, and Identification of the shooter. A ballistic expert need to answer the following questions: 1. Type of The Firearms used 2. Identification of the Firearm 3. Individual Characteristics of Firearm 4. Range of Firing 5. Direction of Firing 6. Identification of the Shooter 7. Medico legal aspects: - Suic

Blood Spatter Analysis

What is Blood Spatter Analysis? Blood Spatter Analysis or Blood Pattern Analysis (BPA) is the examination of bloodstain shapes, locations, and distribution patterns, to provide an interpretation of the physical events that gave rise to their origin. In forensic investigations, it is ubiquitous to encounter blood on the crime scene. This blood can be in the form of a pool, dried stains, spatter, expirated blood, etc. Hence, the investigators are required to understand these bloodstains to interpret the events that have occurred on the crime scene, to create a possible hypothesis of the modus operandi, to identify the type of weapon, the direction of the blow, severity of the injury, applicable forces, etc. This whole interpretation is known as Blood Pattern Analysis or Blood Spatter Analysis. What are the Types of Blood Patterns? There are many classifications given by blood spatter analyst around the world. I will be using the most common here, to make it understand in