1. Introduction to Forensic Sciences.pptx

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1. Introduction to Forensic Sciences

2. Fingerprints Fingerprints are unique patterns, made by friction ridges (raised) and furrows (recessed), which appear on the pads of the fingers and thumbs. Prints from palms, toes and feet are also unique; however, these are used less often for identification, so this guide focuses on prints from the fingers and thumbs. Friction ridge patterns are grouped into three distinct types— loops, whorls, and arches —each with unique variations, depending on the shape and relationship of the ridges

3. Principles of Fingerprinting The two underlying premises of fingerprint identification are uniqueness and persistence (permanence). To date, no two people have ever been found to have the same fingerprints—including identical twins. In addition, no single person has ever been found to have the same fingerprint on multiple fingers

4. Types of Finger Ridge Patterns Loops - prints that recurve back on themselves to form a loop shape. Divided into radial loops (pointing toward the radius bone, or thumb) and ulnar loops (pointing toward the ulna bone, or pinky), loops account for approximately 60 percent of pattern types.

5. Types of Finger Ridge Patterns Whorls - form circular or spiral patterns , like tiny whirlpools. There are four groups of whorls: plain (concentric circles), central pocket loop (a loop with a whorl at the end), double loop (two loops that create an S-like pattern) and accidental loop (irregular shaped). Whorls make up about 35 percent of pattern types .

6. Types of Finger Ridge Patterns Arches - create a wave-like pattern and include plain arches and tented arches. Tented arches rise to a sharper point than plain arches. Arches make up about five percent of all pattern types

7. When and where is fingerprint analysis used? Providing biometric security (for example, to control access to secure areas or systems) Identifying amnesia victims and unknown deceased (such as victims of major disasters, if their fingerprints are on file) Conducting background checks (including applications for government employment, defense security clearance, concealed weapon permits, etc.).

8. When and where is fingerprint analysis used? Fingerprints are especially important in the criminal justice realm. Investigators and analysts can compare unknown prints collected from a crime scene to the known prints of victims, witnesses and potential suspects to assis t in criminal cases. For example: A killer may leave their fingerprints on the suspected murder weapon A bank robber’s fingerprints may be found on a robbery note In an assault case, the perpetrator may have left fingerprints on the victim’s skin A burglar may leave fingerprints on a broken window pane A thief’s fingerprints may be found on a safe

9. In the absence of DNA , fingerprints are used by the criminal justice system to verify a convicted offender’s identity and track their previous arrests and convictions, criminal tendencies, known associates and other useful information. Officers of the court can also use these records to help make decisions regarding a criminal’s sentence, probation, parole or pardon.

10. Fingerprint Analysis Analysts use the general pattern type (loop, whorl or arch) to make initial comparisons and include or exclude a known fingerprint from further analysis. To match a print, the analyst uses the ridge characteristics, to identify specific points on a suspect fingerprint with the same information in a known fingerprint

11. Fingerprint Classification Analysts classify fingerprints into three categories according to the type of surface on which they are found and whether they are visible or not : Fingerprints on soft surfaces (such as soap, wax, wet paint, fresh caulk, etc.) are likely to be three-dimensional plastic prints ; those on hard surfaces are either patent (visible) or latent (invisible) prints.

12. Visible/patent prints are formed when blood, dirt, ink, paint, etc. , is transferred from a finger or thumb to a surface. Patent prints can be found on a wide variety of surfaces: smooth or rough, porous (such as paper, cloth or wood) or nonporous (such as metal, glass or plastic). Latent/invisible prints are formed when the body’s natural oils and sweat on the skin are deposited onto another surface. Latent prints can be found on a variety of surfaces; however, they are not readily visible and detection often requires the use of fingerprint powders, chemical reagents or alternate light sources. Generally speaking, the smoother and less porous a surface is, the greater the potential that any latent prints present can be found and developed.

13. How Fingerprints are Collected Patent Print Collection : Photographed in high resolution with forensic measurement scale for reference. Latent Print Collection : Commonly done by dusting surfaces with fingerprint powder, then lifting prints with adhesive tape onto a latent lift card. Concerns with Fingerprint Powders : They can contaminate evidence and hinder other techniques. Alternatives include alternate light sources (ALS), cyanoacrylate (super glue) fuming, and chemical developers. Alternate Light Source (ALS) : Laser or LED devices emitting specific wavelengths to enhance visibility of prints on surfaces. Cyanoacrylate (Super Glue) Fuming : Exposure of surfaces to cyanoacrylate vapors, which adhere to prints, making them visible under ambient or white light. Chemical Developers : Used on porous surfaces like paper, reacting with latent print residue to reveal prints. Examples include ninhydrin and DFO. Other Collection Methods : Special techniques for skin, clothing, and difficult surfaces, including Amido Black for bloody impressions, vacuum metal deposition for clothing, and AccuTrans® for rough surfaces. Precautions : Nondestructive investigations are prioritized before chemical treatments to preserve evidence integrity. For example, examining documents before applying ninhydrin to avoid ink damage.

14. Paper treated with ninhydrin reagent reveals latent prints after being processed with a household steam iron. (Courtesy of NFSTC) Using a fluorescent dye stain and an orange alternate light source helps this latent print appear clearly so that it can be documented A chamber specially designed for exposing latent prints to super glue fumes. Cyanoacrylate Use of various alternate light sources may help enhance the appearance of a fingerprint.

15. The Development of Forensic Science Laboratory Forensic science in Pakistan has been a key pillar in the criminal justice system. The development of forensic science laboratories in the country has been ongoing since 2001, with authorities revamping forensic science infrastructure across the country to aid crime investigation. Forensic science laboratories have evolved over time, incorporating new technologies and methods. For instance, they now use high-tech robotic workstations to process large numbers of DNA samples simultaneously, allowing for more efficient work ( outside of pakistan)

16. Pakistan, key developments: Punjab Forensic Science Agency (PFSA) : Located in Lahore, the PFSA is the largest forensic DNA laboratory in Pakistan12. It has been helping in solving various cases such as rape, murder, dead body identification, sibship, and parentage2. National Forensic Science Agency (NFSA) : Approved by the Executive Committee of the National Economic Council (ECNEC) as an autonomous body in 2002, the NFSA has departments of crime scene Investigation, trace chemistry, questioned documents, and digital forensics. Forensic Science Laboratory in Peshawar : Established by the Khyber Pakhtunkhwa police in December 2017, this laboratory provides preliminary forensic facilities . Forensic DNA Testing Laboratory in Karachi Universit y: The government of Sindh is making efforts for the establishment of this laboratory. DNA Testing Facility in Jamshoro, Sindh : This facility provides research as well as forensic DNA testing. Forensic Science Laboratory in Swat: A state-of-the-art Regional Forensic Science Laboratory (FSL) has been established at Landaki Swat, with the support from Swiss Development Cooperation (SDC) and the Bureau of International Narcotics and Law Enforcement Affairs (INL)2. Mateen, R.M., Tariq, A. & Rasool, N. Forensic science in Pakistan; present and future. Egypt J Forensic Sci 8, 45 (2018). https://doi.org/10.1186/s41935-018-0077-3

17. Physical Science P hysical science is a branch of natural science that studies non-living systems, the study of the inorganic world and how physical objects behave. It has two main areas: physics and chemistry, with several subgroups, including astronomy and geology. Forensic scientists apply principles of physical science to analyze various types of physical evidence. For example, T hey may use spectroscopy techniques to check the purity of materials or detect illegal drugs . Ballistics : Physics principles are used to analyze firearms, bullets, and cartridge cases to determine the type of weapon, distance, and angle of a shot. Bloodstain pattern : Physics is used to analyze blood spatter patterns to determine the direction, angle, and velocity of blood spatter. Forensic engineering: Physics principles are used to investigate accidents, structural failures, and other incidents. Crime scene reconstruction: Physics is used to analyze accidents, suicides, homicides, and other crime scenes. Density and refractive index measurements: Physics is used to measure density and refractive index in soil, glass, and paint examinations.

18. Biology Biology is the scientific study of living organisms and their interactions with each other and their environments. It encompasses a wide range of topics, including the structure, function, growth, evolution, distribution, and taxonomy of living organisms. Biology provides forensic scientists with valuable tools and techniques to analyze evidence and aid in criminal investigations, helping to bring perpetrators to justice.

19. Document Analysis Document analysis in forensic science, also known as Forensic Document Examination (FDE), is a critical aspect of investigative procedures. It involves the scientific analysis of documents to establish their authenticity, origin, and potential alterations. Documents” may be defined broadly as being any material bearing marks, signs or symbols intended to convey a message or meaning to someone.

20. Photographic Analysis Photographic analysis in forensic sciences is a crucial tool that provides investigators with a visual record of the crime scene , serving as a foundation for further examination and analysis Forensic image analysis is the systematic examination of visual evidence, such as photographs, videos, and digital images, to find relevant information that can help with investigations and legal proceedings

21. Methods used to compare Printers, Copiers and Fax machines Microscopical Reflection-Absorption Infrared Spectroscopy (R-A IR): This technique is used for analyzing the polymer resins contained in dry, black photocopy and printer toners. The sampling technique involves a heat transfer of the toner from a document to the reflective surface of aluminum foil followed by analysis by R-A IR1. A searchable spectral library was created that contains 807 toner samples analyzed by R-A IR1. Machine Identification Code Technology : This technology is used in color laser printers. It helps in identifying the source of a document. Visual Examination and Optical Microscopy : These techniques are used to characterize toners.

22. Scanning Electron Microscopy (SEM) : SEM is used to analyze the physical and chemical properties of toners. Infrared Spectroscopy (IR) : IR is used to identify the chemical composition of toners. P yrolysis Gas Chromatography and/or Mass Spectrometry (Py-GC, Py-GC/MS, Py-MS): These techniques are used to analyze the chemical properties of toners. Differential Scanning Calorimetry (DSC) : DSC is used to measure the heat flow associated with phase transitions in toners1.

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