How it Works
Fingerprinting: An impression on a surface of the curves formed by the ridges on a fingertip especially such an impression made in ink and used as a means of identification.
To start there are 2 main kinds of fingerprints :
- Latent: Made from sweat and oil on the skins surface and invisible to the naked eye.
- Patent: Made by blood, grease, oil or dirt and is easily visible.
They both require different methods of collection but afterwards the same processes are used. Depending on where and what type the prints are determines how they will be collected. On surfaces that absorb liquid (e.g. paper) a chemical called ninhydrin is used over the fingerprints and as they develop detailed photographs are taken. However, on surfaces that do not absorb liquids (e.g. glass) the scientists will use powder and brush techniques followed by lifting tape to take the actual imprint of the fingerprint back to the lab.
Once the prints have been collected and taken back to the lab they will be analysed. When prints are analysed it is first determined if there is even enough information to be put into a category, let alone narrow down to an individual person. The categories are about the patterns (arches, loops and whorls) and from that individual characteristics are determined. These are small differences that make everybody's fingerprints different.
After analysis the prints are compared. This is when there is a known print and a suspects print (or vice versa) and they are compared to either prove guilt or innocence. They are compared very carefully by professionals.
After this they are evaluated, this is when it is decided whether they are an official match, unidentifiable or not matching.
Finally, there is a verification of the evaluation and this is just a second opinion ensuring that combined the right decision has been made. In these cases there are databases available such as Automated Fingerprint Identification System (AFIS) they allow for fingerprints to be identified much faster and are often used in criminal cases.
To start there are 2 main kinds of fingerprints :
- Latent: Made from sweat and oil on the skins surface and invisible to the naked eye.
- Patent: Made by blood, grease, oil or dirt and is easily visible.
They both require different methods of collection but afterwards the same processes are used. Depending on where and what type the prints are determines how they will be collected. On surfaces that absorb liquid (e.g. paper) a chemical called ninhydrin is used over the fingerprints and as they develop detailed photographs are taken. However, on surfaces that do not absorb liquids (e.g. glass) the scientists will use powder and brush techniques followed by lifting tape to take the actual imprint of the fingerprint back to the lab.
Once the prints have been collected and taken back to the lab they will be analysed. When prints are analysed it is first determined if there is even enough information to be put into a category, let alone narrow down to an individual person. The categories are about the patterns (arches, loops and whorls) and from that individual characteristics are determined. These are small differences that make everybody's fingerprints different.
After analysis the prints are compared. This is when there is a known print and a suspects print (or vice versa) and they are compared to either prove guilt or innocence. They are compared very carefully by professionals.
After this they are evaluated, this is when it is decided whether they are an official match, unidentifiable or not matching.
Finally, there is a verification of the evaluation and this is just a second opinion ensuring that combined the right decision has been made. In these cases there are databases available such as Automated Fingerprint Identification System (AFIS) they allow for fingerprints to be identified much faster and are often used in criminal cases.