Fingerprinting

Introduction: (Initial Observation)

Look at the palm of your hands and fingertips. you will see patterns of ridges that are called fingerprints. The natural body oils and sweat collects in these ridges of skin so that when you touch things, you leave behind an impression of your print. Fingerprint ridges are useful because they give your hands a better grip when you pick something up. But since fingerprints are unique, they have also become a common and foolproof method of identification. They can be used to help solve crimes by identifying criminals.
The two basic ideas scientists believe about fingerprints are:

• Fingerprints never change. Small ridges form on a person’s hands and feet before they are born and do not change for as long as the person lives.
• No two fingerprints are alike. The ridges on the hands and feet of all persons have three characteristics (ridge endings, bifurcations and dots) which appear in combinations that are never repeated on the hands or feet of any two persons. A ridge ending is simply the end of a ridge. A bifurcation is a Y-shaped split of one ridge into two. A dot is a very short ridge that looks like a “dot”.

Problem Statement: (Sample)

After each crime, detectives need to find and collect any thing that may possibly lead them to the person or persons who took part in the action. Finger prints are among the most important evidence that can be used to relate a person to a crime. The problem is that finger prints are not visible and we need to use special methods to revel and collect them. This project is an attempt on revealing and identifying finger prints.

Information Gathering:

We start our research by looking at your own fingertips. They are covered with tiny lines and the lines form patterns on our fingertips such as circles, loops, and arches. The patterns are not the same in all our fingers. The lines continue all the way down the fingers and palm, and stops at the wrists.

 

 

 

More information:

The basic fundamentals in the science of fingerprint identification are permanence and individuality.

Permanence: Fingerprint ridges are formed during the third to fourth month of fetal development. These ridges consist of individual characteristics called ridge endings, bifurcations, dots and many ridge shape variances. The unit relationship of individual characteristics does not naturally change throughout life… until decomposition after death. After formation, an infant’s growing fingerprint ridges are much like drawing a face on a balloon with a ball-point pen and then inflating it to see the same face expand uniformly in all directions. Unnatural changes to fingerprint ridges include deep cuts or injuries penetrating all layers of the epidermis and some diseases such as leprosy.

Permanent scars, disease damage, and temporary changes such as paper cuts appear as jagged edges and sometimes “puckered” ridge detail in opposition to smooth flowing natural formations. Warts can come and go, but generally push apart an area of friction ridges and can disappear completely when the wart is gone because they are not a part of the friction ridge structure. Look at a wart with a magnifying glass and you will notice that the friction ridges “surround” the wart. Senile atrophy of friction skin due to old age causes the ridges to often almost flatten, causing fingerprints with many creases (creases are also unique but not always permanent) and poorly defined ridges. Oddly, newborn infants also often have more creases than clearly defined ridge detail in their barefoot prints. The creases are unique, but change relatively rapidly and often disappear as the infant grows. The best chance of seeing friction skin ridges on newborn infant footprints is to look carefully with a magnifying glass on and near the big toe.

Individuality: In the over 140 years that fingerprints have been routinely compared world wide, no two areas of friction skin on any two persons (including identical twins) have been found to contain the same individual characteristics in the same unit relationship. This means that in general, any area of friction skin that you can cover with a dime (and often with just a pencil eraser) on your fingers, palms, or soles of your feet will contain sufficient individual characteristics in a unique unit relationship to enable positive identification to the absolute exclusion of any other person on earth. Recent studies comparing the fingerprints of cloned monkeys showed that they, just like identical twin humans, have completely different fingerprints. When doctors state that twins have the same fingerprints, they are referring to the class characteristics of the general ridge flow, called the fingerprint pattern. These loop, arch and whorl ridge flow patterns have nothing to do with the individual characteristics used to positively identify persons. Before modern computerized systems, fingerprint classification was essential to enable manual filing and retrieval of fingerprints in large repositories.

Today there are more than 250 million criminal and civil fingerprints on record in the U.S.A., with that number increasing by about 34000 each day! All of these fingerprints used to be kept on file cards. Now all of the fingerprint cards are in the computer system, which matches prints in fraction of time.

When DNA evolved as a science, the term “DNA fingerprinting” was adopted to lend credibility to that science’s newcomer status which is in its infancy compared with the empirical validation of fingerprint identification world wide. DNA analysis as commonly practiced in forensic science laboratories cannot differentiate between identical twins, but fingerprints have always been able to differentiate identical twins.

Making fingerprints visible:

Fingerprints that are left behind on objects are called latent fingerprints. The word latent means “hidden,” and these fingerprints are often nearly invisible.

You can make these fingerprints visible by sprinkling them with one of the fingerprint powders. Commonly used fingerprint powders are talcum and graphite. Talcum is white and graphite is black. Any other fine powder may have similar results. Here is how to do it:

1. Make a good latent print with one of your own fingers.

2. Shake out a very small amount of fingerprint powder next to the fingerprint. You need only a very small amount. Remember, one of the most common mistakes is to use too much powder.

3. Use a fluffy feather as a brush and dust the powder lightly back and forth over the fingerprint with your feather brush.
If you look at the feathers, you will notice that the tip of each feather is fairly stiff. But further down towards the handle there are several fluffy, hair-like parts of the feather. These are softer and less stiff then the tip. Use these soft plumes to brush the powder back and forth over the print.

Brush softly, brush lightly, and keep brushing until every detail of the print is clear. The two commonest mistakes are brushing too hard and not brushing enough.

4. When you have finished brushing, blow lightly across the print to remove the excess powder.

Lifting the print:

You can pick up the print you have just finished brushing and preserve it on a piece of paper or on a card. Here’s how to do it.

1. From the sheets of tape squares, peel off one square (or cut a square from any clear adhesive tape). Touch only a tiny corner of the square when you handle it. You don’t want to get a fingerprints on it when you are taking it off the backing paper.

2. Position the tape over the fingerprint. Then lower it until it rests on top of the print. You may smooth it down gently, but don’t rub hard, as this will cause it to smudge.

3. Pick up the tape again by one corner. It will lift up the fingerprint with it.

4. Place the tape on a piece of paper. If the print was made with graphite, place the tape on a white background. If it was made with talcum powder, use a black background.

Classifying fingerprints:

All the fingerprints in the world consist of three basic patterns: Arch, loop and whorl. Within these three basic groups they are further divided into the following subcategories:

ARCHES (about 5% of all fingerprints):

Plain Arch, shaped like a low, rounded hill.	Tented Arch, shaped like a high, pointed hill.

LOOPS (about 65% of all prints):

Ulnar loop, looks like a upside down U and stands toward the little finger side of the hand. Named after the ulna, the arm bone on that side of the arm.	Radial loop, looks like a upside down U and stands toward the thumb side of the hand. Named after the radius, the arm bone on the thumb side.

WHORLS (about 30% of all prints):

Plain Whorl, a pattern of circles or ovals that looks like a target.	Central pocket loop, looks like a whorl tucked inside a loop. It’s classified as a whorl, even though it’s called a “loop.”

 

Double loop, an S-shape	Accidental Whorl, a catchall name for odd patterns that don’t quite fall into the more common groupings. An accidental whorl may contain two or more of the other patterns.

 

As a warm-up experiment try to classify your own fingerprints. Use a magnifying lens to examine them carefully. What do you see? Classify your fingerprints and record the result in a table like this:

	Left Hand	Right hand
Thumb
Index Finger
Middle finger
Ring finger
Little finger

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this project is understanding and experimenting the science of fingerprinting. You may also test different powders to see which one can more clearly reveal fingerprints.

After you learn more about finger prints, you may also come up with additional questions such as:

• What is the most common thumb print? (Main Question)
• How similar are the finger prints of children to the finger prints of their parents?
• Do identical twins have identical finger prints?
• Do cats have finger prints?
• Do dogs have finger prints?
• Any of the above questions can be the subject of a different science project.

Need a graph?

Fingerprinting can help us to classify or identify people based on their fingerprints.

Science Project is a good opportunity for a student to learn about collecting data and making graphs. Following is a more specific question related to fingerprinting that requires collecting data and making a graph.

Which of the three basic fingerprint patterns (Arch, loop and whorl) are the most common for the thumb?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

This is how you may define variables for the question “What is the most common thumb print?”.

Independent variable is the pattern of thumb prints.

Dependent variable is the number of people that have each specific thumb print.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. Also make sure to view the information about defining a hypothesis in the “How to Start” section.

Following is a sample hypothesis for the question “What is the most common thumb print?”. This hypothesis is being tested in experiment number 3.

My hypothesis is that Arch is the most popular thumb print. My hypothesis is based on my observation of thumb prints in my family members.

If you are selecting any other question, you must come up with your own hypothesis.

Experiment 1:

Collect some fingerprints from classmates or family members. Then you find an object such as a glass cup and try to find out who has touched that glass cup. Use a card similar to this to collect and keep the prints.

Print and use this card with the ink pad to record fingerprints of friends and family. You will use these cards to identify fingerprints you discover, as well as for solving mysteries in the future. Begin by making your own fingerprints.

In order to make a clear fingerprint, wash and dry your hands before you start. The above card has space for two kind of impressions.

1. The Rolled Impression: Roll the top part of each finger on the ink-pad and then roll it on the card, in the appropriate space for that finger.

2. Plain Impression: These are used to verify the correct order of the rolled prints. You should take the four fingers and press them down on the ink-pad and then press on the card at the same time (large white space), then make a thumb print next to them.

After each fingerprinting, clean your hand with rubbing alcohol and paper towel.

Rubbing alcohol is flammable. Adult supervision is required.

Coding and Classification: (Additional information for advanced level students only)

After you collect fingerprints on cards, you may want to convert them to codes to create a computer file of your prints. National Crime Information Center has a coding system that you might use.

FINGERPRINT CLASSIFICATION (NCIC) CODE TABLE

If you have ever noticed on a criminal history return a field named FPC/ and followed by a 20 digit number then you have seen an NCIC classification before. Most all criminal histories and some NCIC wanted hits will have this information. Because of the probability of the wanted hit having an NCIC classification it may be an asset to understand just exactly what it means.

A typical NCIC classification might look like this:

FPC/ 19PIPOPM1716PO18PICI

Obviously since most of us have 10 fingers and this is a 20 character string we can pretty safely assume that each two characters represent one finger on the person. The numbering always begins with the number 1 position which happens to be the right thumb and then traveling across the right hand to the right little finger which is #5. The thumb of the left hand is #6 and across to the left little finger which is #10.

Assuming you now understand the scheme of this character string lets move on to what each type of two character string represents. Anytime you see two numbers together, such as 02, 09, 11, 15 etc then you know that the pattern type is a loop pattern. In the case of the 1st two digits of the code above (which is the right thumb) you should know that the thumb is a loop pattern with a ridge count of 19. You can find more information about ridge counts on the loop definition page.

The second finger shown above is the right index finger, which is finger #2, and the code above is PI. This code represents two things, one is the pattern type denoted by the P which means plain whorl and the second character is the tracing of the pattern. In this case it is an inside tracing.

NCIC Codes for the fingers are as follows:

Pattern Type	Pattern Subgroup	NCIC FPC Code
Arch	Plain Arch	AA
	Tented Arch	TT
Loop	Radial Loop	51 – 99: Two numeric characters. Determine actual ridge count and add fifty (50). For example, if the ridge count of a radial loop is 16, add 50 to 16 for a sum of 66. Enter this sum (66) in the appropriate finger position of the FPC Field.
	Ulnar Loop	01 – 49: Two numeric characters indicating actual ridge count (less than 50). For example, a ridge count of 14, enter as 14; a ridge count of 9, enter as 09.
Whorl	Plain Whorl	PI (Inner Tracing ) PM (Meet Tracing ) PO (Outer Tracing)
	Central Pocket Loop Whorl	CI (Inner Tracing) CM (Meet Tracing) CO (Outer Tracing)
	Double Loop Whorl	DI (Inner Tracing ) DM (Meet Tracing ) DO (Outer Tracing)
	Accidental Whorl	XI (Inner Tracing) XM (Meet Tracing) XO (Outer Tracing )
Missing/Amputated Finger		XX (Preexisting Condition)
Scarred/Mutilated Pattern		SR (Preexisting Condition)

For more details visit:
http://www.brazoria-county.com/sheriff/id/fingerprints/index.htm

Now find some latent fingerprints, make them visible and lift them using a clear tape.
When you collect and lift fingerprint specimens, place them on a card like the following picture to keep track of possible suspects. If you have used a white powder, place it on the black square and if you have used black powder, place it on white square.
Look at the print and determine which type of print they are and mark the appropriate box on the left. Also on the card write the location that the print was found.

Try to identify the latent fingerprints that you have found.

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Experiment 2: Touch a smooth surface such as a glass surface with both hands. Then try to reveal the prints with different powders and compare the results. Some of the powders that you may test are: Talcum, graphite, cocoa, Titan (Titanium Oxide) or any other fine powder paint.

Experiment 3: Which of the three basic fingerprint patterns (Arch, loop and whorl) are the most common for the thumb?

Procedure:

1. Prepare 20 small cards, one inkpad and some alcohol pads.
2. Determine 20 different individuals that you can take their thumb prints.
3. Have each person to push his/her thumb on the inkpad and then do the same on one blank card. Give the person an alcohol pad to remove excess ink from his/ her hand.
4. After you collect 20 thumb prints on 20 cards, compare the type of print with samples provided above and determine if it is Arch, Loop or Whorl.
5. Record your results in a table like this:

Type of print	Number of each type
Arch
Loop
Whorl

Make a Bar Graph:

A bar graph that you make for your results will have three bars. Bars will be named Arch, Loop and Whorl.

The height of each bar is the number of people in each type. For example if 7 people have arch thumb prints, then the arch bar will be 7 inches high.

Materials and Equipment:

Material that you need for fingerprinting are as follows:

1. Magnifier, to help you see the details of a fingerprint
2. Feather, Soft fluffy feather used as a brush
3. Plastic tube, (straw) used as a handle for the brush
4. Talcum powder (white)
5. Graphite (black)
6. Ink pad, for making fingerprint for your file
7. Mirror, to help you see fingerprints on your toes and feet
8. Rubbing alcohol, to clean your fingers after print
9. Paper towel, to clean your fingers after print
10. Sheets of clear tape, similar to sheets of labels, but clear
11. White cards or papers

Material for fingerprinting can be purchased as a kit from MiniScience.com or individually from pharmacies and office suppliers.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Summery of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

We found out that fingerprints are not Hereditary as we know we also know that no two fingerprints are alike, and not even identical twins have the same fingerprints.
People may have the same type of fingerprints in a family. This does not mean that they are hereditary. We also know how to lift and examine fingerprints

Related Questions & Answers:

Use a flashlight to search for fingerprints in your house at night. Are the prints easier or harder to find?

Use a mirror to examine your toe, foot and lip prints _ Do they have the same kind of patterns as your fingerprints?

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Related Activities:

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

Visit your local library and find available books and magazine articles related to fingerprinting. You may such references for additional information that you may need. List your references in your bibliography.
To see a short bibliography Click here.

You may find a long bibliography at http://www.scafo.org/Online_Information/bibliography.htm

Following are some additional references.

http://www.brazoria-county.com/sheriff/id/fingerprints/index.htm

This well organized and attractive display is made by Cody Sposato, 5th grade.
He took thumbprints of all fifth graders and showed that loop is the most common pattern for thumb prints.

Photo: Courtesy of Tiffany K Graves, (Cody’s mom)

Question: My question for my fingerprinting project is “what method works best to identify a person’s fingerprints?”. Can you help me determine what other methods there are besides dusting? Or is dusting the only way and you use different types of dust to figure out the best outcome?

Answer: Since you have access to the people whom you want to compare their fingerprints, you don’t have to use dusting method. Just buy an inkpad, some rubbing alcohol and some paper towels. Ask every person to push his/her finger on the inkpad and then push the same finger on the paper you have prepared. They can later use rubbing alcohol and paper towel to clean the ink from their fingers.