science olympiad forensics – Flashcards

thin, central structure of the follicle whose function is undetermined. In forensics, it is important to remember that not all hair follicles found may be human. To tell the species of origin, forensic analysts look to see the pattern of fractures on the medulla, if any.

the middle layer of the follicle containing the pigments: made up of a complex pattern of air pockets, and differently shaped pigment particles. Forensic analysts take advantage of these unique arrangements to identify whose hair it is

the external layer of cells resembling a shell of translucent fish scales or a mosaic. Forensic analysts can use the pattern to determine species of origin and possibly match the follicle to another human if that's what it is

the part of the hair located under the skin (all previously mentioned components of the follicle are located in the shaft, which is the part sticking out of the skin) in the tube-like structure known as the follicle. It is where the hair first begins to grow, the underlying cells forming the protein keratin which comprises the hair.

cuticle pattern resembles that of unorganized, overlapping roof shingles. Only human hairs can possess fragmented or absent medulla.

Shaft diameter: moderate with little variation, Cross Section: oval, Pigment granules evenly distributed

Shaft diameter: fine to moderate with considerable variation, Cross Section: flattened, Pigment granules: clumped

Shaft diameter: moderate with little variation, Cross Section: round, Pigment granules: large patchy areas

the line-like, raised formations that form the pattern that forensic scientists use to analyze and identify fingerprints. By all means, they alone with the furrows they create define the fingerprints. When they form is when a fetus gets his/her fingerprints (more notes on fingerprint formation are listed below)

a point on a fingerprint in which a single ridge divides into two

formation in which the ridge is shaped like a dot

an often elliptically-shaped, bowl-like furrow surrounded by ridges

the most common basic pattern of the human fingerprint, formed by several sharply rising elongated-U-shaped ridges

one of the basic patterns of the human fingerprint, formed by several complete circular ridges one inside another

one of the basic patterns of the human fingerprint, formed by several curved ridges one above the other

1. latent 2. visible 3. impression

composed of several chemicals exuded through the pores in the fingertips and are left on virtually every object touched, hard to find if possible at all, to identify a latent fingerprint, one uses chemical tests

relatively easy to find and photograph

still relatively easy to find and photograph

a method of creating a copy of finger print found at a crime scene which can then be taken back to the crime lab for examination. This process centers on adhering the fingerprint oils which left the ridge imprint to a certain substance (coming in the form a fine powder, hence the term dusting) which can then be pulled up via specialized tape. This is usually then attached to a note card or object of that nature so that one is left with a mirror image of the fingerprint.

regular and magnetic powder

preferable when dusting off such surfaces as windows, televisions, kitchen counter tops, table tops, painted surfaces, cabinets and many other surfaces found in residential and commercial settings, and it is quite effective in dustings on apprehended or stolen vehicles on painted surfaces on the exterior of the vehicle and on glass. It also has the advantage of being available in different colors ranging from black to pink, which makes the fingerprint copy generally more discernible against any debris that the adhesive tape may peel off the surface as well. When utilizing this type of powder, one should use a fiberglass brush. Also, it is important to not get too much powder on it at a time, or you risk compromising the fingerprint. Lightly dapple the tip.

Magnetic powders are best applied to shiny surfaces, such as plastic containers. When dusting for fingerprints with magnetic powder, crime scene investigators must use a magnetic applicator which has a magnet. Magnetic powder is applied with a light hand with brushing strokes. Besides being available in the colors of black, white, silver/gray and biochromatic, magnetic powder is also available in fluorescent magnetic powder colors like red and green. These can be used when dealing with problematic background fluorescence, and they are best applied with feather duster.

an excellent way to develop prints on flexible, porous and non-porous surfaces such as paper, index cards, magazines, and cardboard. To fume a suspected latent print, the surface must be placed into a container with solid iodine. The sublimation of iodine in a closed container will cause iodine vapors to concentrate, then be absorbed by the oil and sweat left behind by human skin. The temporarily-developed print will then be visible as an orange/brown outline. Upon development, the print should be photographed for documentation. The iodine will eventually sublime from the surface of the print, allowing the print to return to its latent state. The surface is then returned to its original appearance and can even be exposed to additional developing techniques.

also called superglue method. Most liquid super glues are really either methylcyanoacrylate or ethylcyanoacrylate. Less common types of super glue include butylcyanoacrylate and isobutylcyanoacrylate. Fortunately, all these types of super glue are nearly identical physically and chemically. Super glue reacts with the traces of amino acids, fatty acids, and proteins in the latent fingerprint and the moisture in the air to produce a visible, sticky white material that forms along the ridges of the fingerprint. The final result is an image of the entire latent fingerprint. This image can be photographed directly, or after further enhancement. However, the glue must be in gaseous state. To do this, one places the surface suspected of containing a latent fingerprint in a container with a heater in it. Then, they place a small, opened container of the glue on top of the heater, and carefully seal the overall one. After that, simply wait.

Ninhydrin is a chemical that reacts with amino acids to form a purple compound. This development technique is used primarily on porous surfaces such as paper, tissue, and clothing. The white powder ninhydrin must be dissolved in acetone before it can be soaked into a surface for development. The reaction will then develop the print within twenty four hours, though that time can be significantly reduced if heated the treated print is heated during development.

How to Perform a Chromatogram on a Pen: 1.Take a wide rectangular piece of filter paper and use a pencil to draw a line about 1.5 cm from the bottom edge of 1 long side. 2. Place small dots of each of the known materials you are to test spaced about 1 cm apart along the line you just drew. Be sure to label what the dots are on the paper ABOVE the dot. 3. Roll the paper up like a cylinder & staple the ends together. 4. Put about 1 cm of water in a Petrie dish. 5. Set your chromatography paper in the dish with the dot side down. Be sure the water level in the Petrie dish does not touch any of the dots on the line you made. 6. While that chromatogram is developing do the same thing over for the knowns of another set of materials. 7. Take 2 strips of chromatogram paper and make a line about 1.5 cm from the bottom with a pencil on each. 8. Bring your prepared pieces of chromatogram paper to the instructor who will place a dot on the papers as your unknowns. 9. Hang the papers in a beaker by placing a wooden stick through the hole in the top & resting the wooden stick on the lip of the beaker. 10. Use your wash bottle to put enough water in the beaker so that the bottom of the chromatograph paper just is in the water, but not so much that the dots are in the water. Be sure that you do not get any water on the chromatography paper as you are putting it in. 11. The chromatograms are done when the water level gets up to about 1.5 cm from the top. 12. Take the chromatograms out and spread them on a paper towel to dry. 13. Which of the knowns do your "crime scene" chromatograms match up to?

1. Splice the DNA into fragments via restrictor enzymes. 2. Insert the fragments into the small pits at the top of a electrophoregram gel pad (put all of the fragments from a single DNA sample into one pit) 3. Put the pad into the gel electrophoresis machine. 4. When it is done, look at the pad. If the dark spots created by a DNA sample are in the same place related to the length of the pad as another sample, the two belong to the same person.

The electrophoresis machine creates a negative electric current at the top of the gel pad (the place where the pits are located) and a positive current at the bottom. This causes the DNA fragments to run down the gel pad. Each fragment is a different size and weight. The heavier it is, the closer to the top it will be, while the lighter, the farther it will run down to the bottom. In the places where a DNA fragment remains, a dark splotch shows up on the pad. If the same type of enzyme is used as the restrictor enzyme, the same distribution should occur in the any sample of the same DNA. That means the splotches for each sample of the same DNA will be in the same place lengthwise along the pad, allowing you to determine if the two samples do in fact belong to the same person.

Calliphoridae (blow flies) and Sarcophagidae (flesh flies) may arrive within 24 h of death if the season is suitable or within minutes if blood or other body fluids are present. A blowfly is shown above. For better prictures than the crap Quizlet has to offer, defer to research.

EGGS- Calliphoridae eggs are usually laid on the body's natural orifices (ears, eyes, nose, and genitals) or any open wounds. This means that if there is a large blow fly population on one part of the body, there has probably been some sort of trauma or injury to that area. When the egg is laid it will be approximately 2mm long. These eggs develop very quickly, and after approximately 8 hours, the egg will start to show signs of change. These eggs will then hatch after about one day.

There are three stages of larvae development in calliphoridae. The first is about 5mm long, 2 days after hatching from the egg. The next instar (as these stages are called) is about 10mm after 2 and a half days. The third and final stage is approximately 17mm after 4 to 5 days. In order to reach each of these stages a larva has to molt.

After the third stage of larval development, the maggot will become uneasy and will start to roam away from the corpse. Their body parts will start to become obscured and we can now call the larva a prepupa. It will be about 12mm long now just 8-12 days after its original egg was laid.

The prepupa will now start to become a pupa. Now 18-24 days after oviposition (egg laying), it will be 9mm long. If an entomologist finds an empty puparia (case of the pupa), you can generally tell that the person has been dead for about 20 days.

metallic blue, black or green in color. Their antennae are covered in fine filaments or branches, giving them a distinctly feathery appearance., range in size from 6 to 10mm

Classified by blood drops traveling through the air at over a hundred feet per second, this can appear as either a mist, or a fine spray of droplets between .1 and 1 millimeter in diameter (these can help determine the direction from which the victim was hit).

Gunshot - will usually result in a mist radiating from the point where the bullet impacted the wall (directly behind the point of impact on the victim). Other weapons can also facilitate high velocity spatters if the assailant exerts enough force when wielding one. However, this is usually recognizable from a bullet by a lack of other markers suggesting gunfire.

A medium-velocity spatter is one that has a force of anywhere from 5 to 100 feet per second, and its diameter is one to four millimeters. It can be caused by a blunt object, such as a bat or an intense beating with a fist. It can also result from a stabbing. Unlike with a low-density spatter, when a victim is beaten or stabbed, arteries can be damaged. If they're close to the skin, the victim bleeds faster and blood can spurt from wounds as his or her heart continues to pump. This results in a larger amount of blood and a very distinctive pattern. Remember that if a victim is beaten, there is usually an initial blow which does not result in blood spatter since there is no exposed blood. Also, medium velocity blood spatters can result from blood being flung from a weapon that has already hit the victim once, and is now being going in for another hit. This forms a distinctive pattern on the wall which shows the exact movement of said weapon

A low-velocity spatter is usually the result of dripping blood. The force of impact is five feet per second or less, and the size of the droplets is somewhere between four and eight millimeters (0.16 to 0.31 inches). This type of blood spatter often occurs after a victim initially sustains an injury, not during the infliction of the injury itself. For example, if the victim is stabbed and then walks around bleeding, the resulting drops are a type of low-velocity spatters known as passive spatters. Low-velocity spatters can also result from pools of blood around the body of a victim and transfers (impressions left by weapons, or smears and trails left by movement). It can occur with some injuries, such as bleeding sustained from a punch.

A low-velocity spatter is usually the result of dripping blood. The force of impact is five feet per second or less, and the size of the droplets is somewhere between four and eight millimeters (0.16 to 0.31 inches). This type of blood spatter often occurs after a victim initially sustains an injury, not during the infliction of the injury itself. For example, if the victim is stabbed and then walks around bleeding, the resulting drops are a type of low-velocity spatters known as passive spatters. Low-velocity spatters can also result from pools of blood around the body of a victim and transfers (impressions left by weapons, or smears and trails left by movement). It can occur with some injuries, such as bleeding sustained from a punch.

Multiply the width of the drop divided by the length by the inverse of sin to determine the angle in which the blood impacted the surface. In a single blood spatter pattern, you can connect all of the angles of the individual drops to determine the point of origin.

The A antigen, you have type A blood. The liquid portion of your blood (plasma) has antibodies that fight against type B blood. In the United States, about 40% of the white population, 27% of African Americans, 28% of Asians, and 16% of Native Americans are type A.

The B antigen, you have type B blood. Your plasma has antibodies that fight against type A blood. In the U.S., about 11% of the white population, 20% of African Americans, 27% of Asians, and 4% of Native Americans are type B.

Neither the A nor B antigen, you have type O blood. Your plasma has antibodies that fight against both type A and type B blood. In the U.S., about 45% of the white population, 49% of African Americans, 40% of Asians, and 79% of Native Americans are type O.

Both the A and B antigens, you have type AB blood. Your plasma does not have antibodies against type A or type B blood. In the U.S., about 4% of the white population, 4% of African Americans, 5% of Asians, and less than 1% of Native Americans are type AB.

is the largest particle in the soil. When you rub it, it feels rough. This is because it has sharp edges. Sand doesn't hold many nutrients.

is a soil particle whose size is between sand and clay. Silt feels smooth and powdery. When wet it feels smooth but not sticky.

is the smallest of particles. Clay is smooth when dry and sticky when wet. Soils high in clay content are called heavy soils. Clay also can hold a lot of nutrients, but doesn't let air and water through it well.

• Yellow flame • Plastic drips • Burns slowly • light smoke • Polyethylene Terephthalate is probably most well known for its use in water, juice, and soda bottles. You’ll also find PET plastic used in other packaging such as peanut butter jars, containers for holding salad dressings, cooking oils, cosmetics, and household cleaners. PET used for plastic packaging consumes roughly 30% of PET usage worldwide. • A major use of Polyethylene Terephthalate is in synthetic fibers used for manufacturing polyester clothing, fabrics, carpets, etc. PET used for this purpose consumes more than 60% of PET usage worldwide!

• Orange flame • Self extinguishing • Plastic drips • Black smoke w/ soot (floating particles) • Faint, sweet aromatic odor • Data storage including, CDs, DVDs, blu-ray discs, etc… • Lenses including sunglasses, prescription glasses, automotive headlamps, riot shields, instrument panels, etc… • PC is derived from bisphenol A (BPA) and is no longer used in food applications • Electrical and telecommunications hardware • Construction materials such as dome lights, sound walls, etc… • Automotive, aircraft, and security components • Medical applications

• Yellow flame w/ green spurts • Plastic does not drip • Self extinguishing • Smells like hydrochloric acid • Plastic chars • A large usage of flexible PVC is in wire insulation (colored plastic wrapped around electrical wires). Flexible PVC can be found in clothing such as raincoats, rain boots, and leather-like fabrics. PVCs are also made into vinyl records and vinyl signs and billboards. • About 75% of all PVC resin (rigid) is made into construction materials such as piping & fittings, siding, flooring, windows, fencing, decking, roofing, wall coverings, etc…

• Yellow flame • Burns quickly • Plastic drips • Illuminating gas odor (naphtha) • Dense black smoke w/ soot (floating particles) • CD / DVD jewel cases • Audio and videocassette casings • Model assembly kits • Clear disposable cups • Styrofoam packaging such as boxes, filler material, etc (EPS) • Styrofoam tableware such as cups, plates, containers, etc (EPS) • Building insulation (EPS) • Cases for electronic equipment such as television, air conditioner, and computer cases (HIPS) • Stationary such as pen cases, organizing trays, etc (HIPS) • Toys (HIPS)

• Blue, yellow tipped flame • Burns slowly • Plastic drips • Has sweet odor • Floats in water • A common use of PP is in food containers. PP is naturally BPA free and has a high melting point making it dishwasher and microwave safe. • Due to its resistance to fatigue, most hinge type products are also made from PP (such as flip-top bottles, lock&lock Tupperware, etc…). • PP is often used for storage containers such as Rubbermaid and Sterilite containers. The softer, rubbery lids are made of a softer plastic, usually LDPE. • Products made from PVC and HDPE can also be made with polypropylene. For instance, the infamous PVC piping can also be manufactured using PP. HDPE furniture such as tables and chairs can also be substituted using PP. • PP is commonly used in non-woven fabrics (used in diapers and or sanitary products). • Polypropylene is commonly used for producing ropes, carpets and recycled plastic rugs. • Many stationary products such as plastic folders, notebook covers, paper protectors, storage boxes are also made from PP. These products are made through the plastic extrusion process.

• Blue, yellow tipped flame • Burns slowly • Plastic drips • Smells like candle wax (paraffin) • Floats in water o Hdpe • More than 8 million tons of HDPE are used toward blow-molded containers such as milk jugs, juice containers, detergent bottles, motor oil bottles, trash bins, etc. That is nearly one third of HDPE's annual production worldwide. • A large portion of recycled HDPE plastic is made into composite wood or plastic lumber. • Toys! One third of all toys are manufactured using HDPE. Example of a HDPE toy (click to view image). • Plastic bags with #2 label o Ldpe • grocery bags • Thin packaging (bread, newspaper, dry cleaning, sandwich bags, etc…) • Plastic film (ie., cling wrap, saran wrap) • Squeeze bottles • Six pack rings (for sodas) • Moisture barriers in construction • Agricultural wrap • Plastic laminate for cardboard milk and juice bottles • Flexible parts via injection molding

1.5 degrees F an hour, algor mortis

98.6 degrees F

•The skin turns a greyish-white colour. •The eyes become dull and film over and the pupils dilate. •Skin loses elasticity. •Blood sinks by gravity, turning areas where it settles blue and purple. •Lactic acid is produced in muscles causing the stiffness of rigor mortis. This starts developing one to four hours after death and is complete after 24 hours. The effects can last 36-48 hours.

•The human bowel contains bacteria that multiply rapidly after death. This starts the process of decay and is aided by the enzymes and chemicals also present in the body. •The body will show greenish discoloration on the chest, lower abdomen and thighs. •The putrid smell of death will increase. This is caused by sulphur-saturated gas produced from bacterial action and the breakdown of red blood cells. •Four to six days after death the body will bloat with gas unless an incision is made in the abdomen to release it. The build up of gas causes the eyes and tongue to protrude and the intestines may be pushed into the rectum and vagina. •The body may turn purple and black. •Bloodstained fluid may leak from bodily orifices. The Later Stages of Decomposition A body is normally embalmed or buried within a week but will continue to decompose in the following manner: •A week after death, most of the body will be discoloured and the skin will blister and may lift off the body. •After two weeks the breasts, abdomen, scrotum and tongue swell. •After three to four weeks the hair, nails and teeth loosen and internal organs rupture and liquefy. •If a body is buried, the coffin is likely to disintegrate after a few months and the body will liquefy as a result of chemical action, bacteria and insect activity. •After one to two years, only the skeleton will remain. •Depending on the soil acidity and temperature, bones will take anything from 25 to 500 years

When blood falls from a height or at a high velocity, it can overcome its natural cohesiveness and form these