Labs

Fingerprinting

In this portion of our forensics project, we placed our fingers on a light surface and allowed the grease to from a print. We then gingerly brushed a dark powder on the print so as not to disturb the print's shape and to make it more visible to the naked eye. A piece of tape must be placed over the powder to lift the fingerprint as if at a crime scene. Lastly, the piece of tape with the newly lifted fingerprint has to be applied to a light colored piece of paper in order for further examination and analysis.

In this fingerprinting section of our forensics lab, we were each required to stamp our fingerprints in blue ink and place our prints in the corresponding box. We then identified the types of loops, arches, or whorls present in each fingerprint based on a given picture of each.

Hair/Fiber Analysis

For this lab, our groups had to analyze various samples of hairs and fibers through a microscope and identify unique traits of each. Pictured above, some of the analyzed samples were African-American hair, synthetic hair, dyed hair, nylon fabric, and cotton. Identifying traits include the color of the hair or fiber, the condition of the tip, and any oddities that make the sample easily identifiable.

Lipstick Analysis

For the lipstick analysis, we each had to apply lipstick and place a lip print on a notecard. Easily discernible features of an individual's lip include space between the lips, any scars on the lip, humps/arches, ratio of the size of the top lip to the bottom lip, chapped lips, and the general shape of the lip. As seen above in my lipstick print, I have distinct humps on my upper lip, a small space between by lips, lines running through my bottom lip, and a full bottom lip that is a lot bigger than my top. At a crime scene a lipstick print may be left behind for forensic examiners to analyze. However, the analysis of a lip print won't actually positively identify a single suspect like a fingerprint might.

Handwriting Analysis

Pictured above is one of the exercises we completed to demonstrate forensic handwriting analysis. In the first box is my writing with observations made by a forger. In the second box is a freehand forgery in both print and cursive. As clearly demonstrated, the letters in the forgery appeared very close to the original. However, the line habits are completely off as they slant steeply downward in the forgery. In addition, the ratio of the characters is a lot larger than the original, as are the spaces between the letters. In the third box is a traced forgery, which is understandably a lot more accurate than the freehand. Still, the traced forgery can be identified by the pen pressure. The forger seemed to have pushed down too hard on their pencil in an effort to replicate the original. Also, the line quality is shaky in areas where the forger tried to retrace certain letters, like the "f" in fox. In my opinion, tracing a forgery is a lot easier than freehanding. This is because in freehanding, the forger has to carefully replicate every aspect of the original writing while maintaining a steady speed to avoid shaky letters. In contrast, tracing only requires the forger to be focused on pen pressure, line quality, and simply following the shapes of the letters.

We were also required to write a fake check and tear it into pieces. People in other groups were then supposed to piece the checks back together and compare them to a stack of handwriting samples. We were all successful in my group in determining the writer of the check. The most identifying aspect of the writing was the ratio of characters, the line quality, and the distinctive shape of certain letters in both samples.

Footprint Analysis

For footprint analysis, each person in my group placed their foot in a bin of dirt to analyze details of the bottom of their shoe. The analysis of a footprint can reveal the relative weight of the person, the kind of shoe (revealed by certain patterns), and can positively identify a suspect if the print is very unique and similar to the suspect's shoe. The rarity of the designs on the bottom of the shoe can help solve a case by identifying a single suspect. In this exercise, we analyzed the weather conditions, the substance the print was left in, and important aspects of the footprint (size, writing, designs).

Drug Analysis

Drug	pH	Cocaine Reagent	LSD Reagent	Methamphetamine Reagent
1	5	+	-	-
2	9	+	-	-
3	2	-	+	-
4	8	+	-	-
5	6	+	-	-
6	3	-	+	-

The table above is the information for the drug analysis lab completed in class. We were given six unidentified substances, which were to be tested with various chemicals (cocaine reagent, LSD reagent, and meth reagent). If the substance turned blue in cocaine reagent, cocaine was present. If the substance turned yellow in LSD reagent, LSD was present. We also tested the pH of each liquid. The chart above shows the pH values and which drug was present in which compound. 

Poison

Sample	Metal Poison
1	Pb
2	Fe
3	none

Sample	Sugar
1	No sugar present
2	No sugar present
3	No sugar present

Sample	Odor	pH	Color after PHTH
1	Like cleaning products	11	pink (contains ammonia)
2	odorless	8	colorless
3	odorless	7	colorless

Sample	pH	Color after BTB
1	2	yellow (contains aspirin)
2	8	blue
3	7.5	blue

Sample	Color after Fe+3
1	colorless
2	blood red (cyanide present)
3	colorless

Sample	Color after Starch
1	yellow
2	pink
3	blue (iodine present)

The poison analysis lab was much like the drug analysis lab in that we had to test sets of unknown substances with chemicals to identify harmful poisons that could be contained within the sample. For example, in one of the tests, we had three unknowns that we had to test for ammonia by adding PHTH. We found that samples 2 and 3 remained colorless while sample 1 turned pink, positive for ammonia. These simple chemical tests could help identify the cause of death during an investigation and might even lead to a suspect.

Facial Recognition/Witness Experiment

The witness project was a unique experiment in which we didn't focus on facts or analytical examination but rather human relation and memory. In a group of six, we each cut out similar faces in several different magazines (faces must have same color and same size, otherwise the experiment will be invalid). After the faces were cut out, we cut individual facial features out, like the eyes, nose, mouth, and ears. The whole group placed their pieces in piles according to facial features. We then each drew from the pile pieces that would make a face, not necessarily the same face we had before. The faces were passed amongst ourselves, with ten seconds to memorize everything we could about the other person's constructed face. The faces were disassembled, placed in piles like before, and drawn back out to try to reassemble the memorized face. My results in the test are shown above, and my whole group's results were 100% accurate.

History of Fingerprinting

Fingerprints are the patterns on the tips of every finger. No two people have the same exact fingerprint, with the odds of this occuring being 1 in 64 billion.

The earliest recorded use of fingerprints dates back thousands of years as a mediocre identification system for the Babylonians and a method for recording business transactions for the Chinese. Only until the 19th century was the science applied to identify criminals.

In 1882, Sir Francis Galton, who studied human characteristics, compiled a database of 8,000 fingerprints for his research into a new system for identification. He published a book called Fingerprints, which became the world's first system for analyzing fingerprints, based on simple patterns in fingerprints that are easily identifiable and unique to every person.

In 1901, Scotland Yard, quickly followed by other law enforcement agencies around the world, established a Fingerprint Bureau solely for the purpose of identifying criminals by their fingerprints. This event marked the beginning of the use of fingerprints as the perfect unrefutable and unbiased method to pursue and apprehend criminals.

Before the 1980s, and before Japanese agencies developed an automatic system for fingerprint analysis called AFIS (Automated Fingerprint Identification System), cross-referencing prints lifted at the crime scene with the fingerprints of individuals containing a police record would have to be done manually. This process would take days or more at a time, even with a large workforce, to find a perfect match and a suspect. Understandably, the manpower this method required and the time with which it was done became extremely inconvenient and actually hindered law enforcement agencies. Still, even with their own development of an AFIS system, U.S. law enforcement was still hindered by the lack of coordination between agencies. Local authorities didn't share the same database as state authorities, who still didn't communicate with federal datab ases. Therefore, the AFIS system could only work within a small jurisdiction. That all changed, however, when the IAFIS (Integrated Automated Fingerprint Identification System), was established. This new database allowed the sharing of information between all levels of authorities, making the system faster and more accurate than ever. IAFIS is still in use today, with a databasae containing over 47 million fingerprints.

Types of Fingerprints

There are three basic types of fingerprints that can be used in forensics: direct, latent, and plastic.

Direct

Direct prints are clearly visible to the naked eye. In order for these to occur, the print must be pressed into a substance which would make it visible. These can include blood, dirt, ink, or similar materials. The fingerprint must come in contact with one of the materials and then a surface to leave a direct print.

Latent

Latent prints are formed when the sweat or grease from the finger leaves a print on an object. These fingerprints aren't visible to the naked  eye and must be lifted via dusting or another process to be examined later.

Plastic

Plastic prints are formed when the finger presses into a soft surface to leave behind an impression. Some examples include wax, clay, and soap.

Lifting and Developing Prints

Depending on the surface from which a fingerprint is being lifted, two different procedures may be utilized. On a nonabsorbent or hard surface, examiners use a powder to lift prints. In contrast, on a soft or porous surface, certain chemicals may be used to collect fingerprint evidence.

    Nonabsorbent/Hard Surfaces (wood, tile, glass)

 The color of the powder used at a crime scene depends on the surface from which the print is being lifted. If the surface is of a light color, a black powder will be brushed over the print. If the surface is darker, a light powder will be used. The powder is brushed over the fingerprint carefully so as not to disturb any of the identifiable ridges. Tape is then applied over the print and then reapplied onto a sheet of paper to be analyzed in a lab.

Soft/Porous Surfaces (cloth)

Iodine Fuming- The material from which a print is to be extracted must be placed in an enclosed chamber with iodine crystals. The crystals are heated, forming a vapor which makes the print visible. However, the print will only be visible while the reaction is taking place, so a picture must be taken for examination or the print must be preserved with sprayed 1% solution of starch in water.

Silver nitrate- A powder form of silver nitrate (AgNO₃) must be brushed on the print and exposed to ultraviolet light to make the latent print visible with a very distinguishable color.

Basic Patterns of Fingerprints

Arches

In an arch, the ridges on the fingerprint run straight across the print without redoubling back the way a loop or whorl does. There are two types of arches:



Tented Arch
The arch is very distinctive and thrusts upward
with lines underneath arch appearing curved

Plain Arch
A slight arch appears in the middle of the pattern
with underlying lines remaining consistently straight









          

  

Loops

Loops are ridges which turn or loop back, but don't completely twist in a full circle. Loops are classified by the direction which they flow toward, the radius or the ulna.



Radial Loop
This loop flows toward the radius, considering
that this is a right-handed print

Ulnar Loop
The loop shown above flows left in the direction
of a right-handed ulna

Whorls

In a whorl, the ridges on the print turn completely to make at least one full circuit. This means that at least one complete oval or circle shape will be easily visible.

Double Loop Whorl
Two separately distinct sets of loops which
individually make their own whorls

  

Plain Whorl
The simplest and most common whorl.
Plain whorls curve into only one full circular shape

                                                                                                         



Central Pocket Whorl
At least one ridge curves around to make
more than one full circuit

Accidental Whorl
This distinct set of ridges reveals a plain arch with two
additional types of patterns that make a full circuit

History of Hair/Fiber Analysis and Hair Diagram

Trichology, or the scientific study of hair, was first introduced in 1857 after a report was published in France outlining the possibility of using such analysis at a crime scene. In the beginning of the 20th century, the study of trichology expanded and microscopic examination of hair became widely renowned. Hair evidence wasn't actually used by forensic examiners until a book titled "Microscopy of Hairs: A Practical Guide and Manual" was published in 1977, laying the foundation for hair examination as a form of police work.

Parts of Hair

Follicle- the part of the hair underneath the surface of the skin. Hair grows from the root, supported by glands and their own blood supply. The follicle controls hair growth.

Shaft- the visible part of the hair above the surface of the skin. Consists of the cuticle, cortex, and medulla.

Cuticle- the outermost layer of the hair that protects the underlying layers.

Cortex- surrounds the medulla and contains keratin and melanin, proteins which give the hair its shape and color

Medulla- the central part of the hair. Contains excess cells and usually appears as a shapeless area.

Hair/Fiber Collection Techniques and Analysis

The Crime Scene

During collection of fibers at a crime scene, fibers need only be placed in individual envelopes and marked as evidence. The same holds true for hairs, but if a hair is attached to another object certain steps have to be taken. If the object on which the hair is attached is small, such as a shard of glass, the hair and object must be placed in an evidence envelope and marked. If the object is too large, the are around the hair must be wrapped in paper to prevent loss of hair evidence. Tweezers can be used for removal of hairs or fibers if necessary.

Analysis

Both hairs and fibers are analyzed using microscopy technology to compare samples, but the actual analysis varies between hair and fiber samples.

Hair

Individual strands of human hair, through analysis, can determine the race and relative age of the person from which the sample came as well as from where on the body the hair was located. In addition, dyed hairs are easily discernible under a microscope and can help identify the owner. Analysis of hair roots can determine how the hair was lost from the body. These traits discovered through hair analysis can help narrow the search scope and ultimately lead to the identification of a suspect. DNA can also be extracted from strands of hair to positively identify the perpetrator, instead of just narrowing the search.

Fiber

In contrast, fiber evidence is analyzed to associate a suspect through statistical elimination. Fibers found at the crime scene must be compared to fibers linked to a suspect. Moreover, the fiber has to be proven to be unique and therefore establish odds that the sample collected came from the suspected source. For instance, in the Atlanta Child Murder case, statistical evidence was used to determine that the chance the samples collected belonged to anyone other than the suspect was 1 in 29,827,776.

Reliability

Hair and fiber evidence is usually able to help establish a significant lead in a criminal case, but results based solely off such evidence is rarely considered conclusive. Statistical elimination is helpful in minimizing a list of suspects but ultimately can't be used as conviction-worthy evidence. Only DNA extracted from a hair sample is considered reliable and conclusive.