How to Analyze Fingerprints
Look for prints., Dust for latent prints., Photograph the prints., Determine the type of surface the prints are on., Lift the prints., Match the prints.
Step-by-Step Guide
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Step 1: Look for prints.
In forensic fingerprinting, there are a few types of fingerprints and a few ways to find them.
As you start looking for fingerprints, some will be visible (patent) and others will be invisible (latent).
Search for patent ones first and place a marker of some kind by it remind you later.
To search for latent prints, it can be good to use an alternate light source, such as a blue light with an orange filter.
This helps make latent prints stand out.There are also ones called plastic prints which are in soft surfaces like soap. -
Step 2: Dust for latent prints.
Once you have found the latent prints with an alternative light source, you need to dust them to make them more visible.
Professionals use special powder, but for amateur home use, talcum powder or cornstarch is a great alternative.
You’ll also need a brush with a lot of soft bristles on it.
With the light source still revealing the print, lightly dust the powder over it until it is sufficiently revealed.
When using an alternate light source, it is most effective to turn the other lights in the room off, making the light more powerful. , For patent prints that are already visible and latent prints which you have revealed with light and dust, the best collection method is to take a picture with a high resolution camera.
It is easier to study prints in photo form anyway.
Make sure you take the picture close enough to see the details of the print.
You always want to have a ruler of some kind next to the print to give a scale for how big it is.This is also helpful because it allows you to upload the prints onto the computer for analysis and file storage. , Fingerprints can be found on any surface.
Surface types are categorized into porous, non-porous smooth, and non-porous rough.
Things of a cloth nature, or anything water could seep into, are considered porous.
Non-porous smooth would be things like glass or a varnished table.
Non-porous rough would be a leather couch or a plastic container with a textured edge.This is important because the surface type can either make it easy or hard to lift a good print. , Besides photography, the second way to collect the prints is to lift them with tape or gel.
For smooth surfaces, lay a piece of clear tape over the print gently, then peel it off and place it on a white square of sturdy paper.
You must be careful to lay the tape straight down on the print and not move it side to side at all as this might smudge it.For porous and non-porous rough surfaces, just the photograph is the easiest collection method, but there are other options.
These require something that will get into the grooves, such as gel lifter or superglue.
A gel lifter is a product specifically made for lifting prints from rough surfaces and it is laid over the fingerprint and creates a small 3D cast of the print.
Superglue can be applied to the print and allowed to dry and then peeled off creating a mold.
This gives you a backup to the pictures that you took and allows you to file a piece of physical evidence of the prints. , This is not easily done for someone without training or proper technology.
If you have a set of known prints, you can compare the ones you lifted to those.
Look for similar patterns to rule out some of the prints.
There are advanced computer programs which can read dozens of points on a fingerprint and match those points to other known prints, but this is more for professional endeavors. -
Step 3: Photograph the prints.
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Step 4: Determine the type of surface the prints are on.
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Step 5: Lift the prints.
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Step 6: Match the prints.
Detailed Guide
In forensic fingerprinting, there are a few types of fingerprints and a few ways to find them.
As you start looking for fingerprints, some will be visible (patent) and others will be invisible (latent).
Search for patent ones first and place a marker of some kind by it remind you later.
To search for latent prints, it can be good to use an alternate light source, such as a blue light with an orange filter.
This helps make latent prints stand out.There are also ones called plastic prints which are in soft surfaces like soap.
Once you have found the latent prints with an alternative light source, you need to dust them to make them more visible.
Professionals use special powder, but for amateur home use, talcum powder or cornstarch is a great alternative.
You’ll also need a brush with a lot of soft bristles on it.
With the light source still revealing the print, lightly dust the powder over it until it is sufficiently revealed.
When using an alternate light source, it is most effective to turn the other lights in the room off, making the light more powerful. , For patent prints that are already visible and latent prints which you have revealed with light and dust, the best collection method is to take a picture with a high resolution camera.
It is easier to study prints in photo form anyway.
Make sure you take the picture close enough to see the details of the print.
You always want to have a ruler of some kind next to the print to give a scale for how big it is.This is also helpful because it allows you to upload the prints onto the computer for analysis and file storage. , Fingerprints can be found on any surface.
Surface types are categorized into porous, non-porous smooth, and non-porous rough.
Things of a cloth nature, or anything water could seep into, are considered porous.
Non-porous smooth would be things like glass or a varnished table.
Non-porous rough would be a leather couch or a plastic container with a textured edge.This is important because the surface type can either make it easy or hard to lift a good print. , Besides photography, the second way to collect the prints is to lift them with tape or gel.
For smooth surfaces, lay a piece of clear tape over the print gently, then peel it off and place it on a white square of sturdy paper.
You must be careful to lay the tape straight down on the print and not move it side to side at all as this might smudge it.For porous and non-porous rough surfaces, just the photograph is the easiest collection method, but there are other options.
These require something that will get into the grooves, such as gel lifter or superglue.
A gel lifter is a product specifically made for lifting prints from rough surfaces and it is laid over the fingerprint and creates a small 3D cast of the print.
Superglue can be applied to the print and allowed to dry and then peeled off creating a mold.
This gives you a backup to the pictures that you took and allows you to file a piece of physical evidence of the prints. , This is not easily done for someone without training or proper technology.
If you have a set of known prints, you can compare the ones you lifted to those.
Look for similar patterns to rule out some of the prints.
There are advanced computer programs which can read dozens of points on a fingerprint and match those points to other known prints, but this is more for professional endeavors.
About the Author
Kathryn Campbell
Professional writer focused on creating easy-to-follow organization tutorials.
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