Fingerprint Examination

Fingerprint examination

R.C.M.P.

© R.C.M.P.. All Rights Reserved.


A fingerprint is a mark left behind after the ridges on the fingers, hands, toes or feet touch an object. There are two types of prints: a direct fingerprint (it creates an impression) and a latent print (dirt, sweat or other residue that is pressed onto another object). Fingerprints have three main classes: the arch, whorl and loop. Within these three classes, there are an immense number of patterns that are different for each one of us. Aside from scars, there are forks, islands or spaces where the lines of a fingerprint make different latent prints.
A fingerprint is a mark left behind after the ridges on the fingers, hands, toes or feet touch an object. There are two types of prints: a direct fingerprint (it creates an impression) and a latent print (dirt, sweat or other residue that is pressed onto another object). Fingerprints have three main classes: the arch, whorl and loop. Within these three classes, there are an immense number of patterns that are different for each one of us. Aside from scars, there are forks, islands or spaces where the lines of a fingerprint make different latent prints.

© CHIN. All Rights Reserved.

No two fingerprints are the same. Fingerprints can be taken even from surfaces which are not smooth (e.g. clothing or paper towel). Even if fingerprints are months or years old, new technology allows scientists to recover fingerprints from objects. Techniques using charged particles or particles that glow under certain conditions are applied to test areas. This allows for testing of larger areas and faster processing of fingerprints at the crime scene.
No two fingerprints are the same. Fingerprints can be taken even from surfaces which are not smooth (e.g. clothing or paper towel). Even if fingerprints are months or years old, new technology allows scientists to recover fingerprints from objects. Techniques using charged particles or particles that glow under certain conditions are applied to test areas. This allows for testing of larger areas and faster processing of fingerprints at the crime scene.

© CHIN. All Rights Reserved.

Paint can be liquid, chip or smears. Paint can be identified by colour, type, texture (glossiness, granularity, hardness, wrinkling, cracking, blistering and chalking properties), layer structure and composition. Once the information is gathered, it can be compared to databases where information is stored about many other types of paint. This way, one can find out details about the clues that have been found. Paint identification can be very useful for hit and run incidents. The victim and the crime scene may have small chips of paint left behind from the assailant’s vehicle that can be taken into evidence. At the lab, the characteristics of the paint are noted and then entered into a database. The databases allow for comparisons of large amounts of data. A match of vehicle paint from the crime scene to that in the database may yield the make, model and year of the car in question which assists the investigating officer as well as the courts during the investigation.
Paint can be liquid, chip or smears. Paint can be identified by colour, type, texture (glossiness, granularity, hardness, wrinkling, cracking, blistering and chalking properties), layer structure and composition. Once the information is gathered, it can be compared to databases where information is stored about many other types of paint. This way, one can find out details about the clues that have been found. Paint identification can be very useful for hit and run incidents. The victim and the crime scene may have small chips of paint left behind from the assailant’s vehicle that can be taken into evidence. At the lab, the characteristics of the paint are noted and then entered into a database. The databases allow for comparisons of large amounts of data. A match of vehicle paint from the crime scene to that in the database may yield the make, model and year of the car in question which assists the investigating officer as well as the courts during the investigation.

© CHIN. All Rights Reserved.

Paint Chip

Paint chip

R.C.M.P.

© R.C.M.P.. All Rights Reserved.


Comparison microscopes are used to see if a hair sample found at a scene matches a known sample. Examination of hair can also determine the animal family of origin, the body area of origin for human hairs and the method of removal from the body, as well as providing an indication of racial origin. Scalp hair can give the scientist the most information because it usually undergoes the most varied treatments (dying, curling, cutting, hairspray, etc...).

Hair comparison is not conclusive and this is the reason why DNA methods may also be used. Since all nucleated cells in the body contain DNA, hair roots and roots sheaths may be used, and the amount of DNA may be amplified using a method called PCR. The DNA is then typed and a match may be found. The first 10 mm of the bottom of each hair may be used for the DNA testing because it contains the root sheath. Although it does not contain nuclear DNA, the hair shaft may be analyzed for mitochondrial DNA.
Comparison microscopes are used to see if a hair sample found at a scene matches a known sample. Examination of hair can also determine the animal family of origin, the body area of origin for human hairs and the method of removal from the body, as well as providing an indication of racial origin. Scalp hair can give the scientist the most information because it usually undergoes the most varied treatments (dying, curling, cutting, hairspray, etc...).

Hair comparison is not conclusive and this is the reason why DNA methods may also be used. Since all nucleated cells in the body contain DNA, hair roots and roots sheaths may be used, and the amount of DNA may be amplified using a method called PCR. The DNA is then typed and a match may be found. The first 10 mm of the bottom of each hair may be used for the DNA testing because it contains the root sheath. Although it does not contain nuclear DNA, the hair shaft may be analyzed for mitochondrial DNA.

© CHIN. All Rights Reserved.

Gunshot Residue Particle on Top of Hair

Gunshot residue particle on top of hair

R.C.M.P.

© R.C.M.P.. All Rights Reserved.


Magnified Hair Sample

Magnified hair sample

R.C.M.P.

© R.C.M.P.. All Rights Reserved.


Learning Objectives

The learner will:
  • Develop enthusiasm and continuing interest in the study of science
  • Describe how the field of genetics relates to forensic science
  • Describe how biology and chemistry are used to solve crimes
  • Describe examples of the application of technology in society

Teachers' Centre Home Page | Find Learning Resources & Lesson Plans