DNA Presentation

MASTER ON CRIMINAL JUSTICE

Topic: CHAPTER X DEOXYRIBONUCLEIC ACID (DNA)

PROFESSOR: RIZALINO D. FLORES III, RC, MA CRIMREPORTER: CEASAR L. ESTRADA II, DSM, CSP JUSMAG PHILS, US EMBASSY

SCIENCE OF CRIMINALISTICS MCJ 203

DNA AS A MEANS OF PERSONAL IDENTIFICATION

DNA TYPING

COLLECTION AND PRESERVATION OF BIOLOGICAL EVIDENCE FOR DNA ANALYSIS

SCOPE OF PRESENTATION

DNA Fingerprint

How Does one Create a DNA Fingerprint ?

The Uses of DNA Fingerprinting ?

DNA AS A MEANS OF PERSONAL IDENTIFICATION

DNA (deoxyribonucleic acid) represents the blueprint of the human genetic makeup. It exists in virtually every cell of the human body and differs in its sequence of nucleotides (molecules that make up DNA, also abbreviated by letters, A, T, G, C; or, adenine, thymine, guanine, and cytosine, respectively). The human genome is made up of 3 billion nucleotides, which are 99.9% identical from one person to the next. The 0.1% variation, therefore, can be used to distinguish one individual from another. It is this difference that can be used by forensic scientists to match specimens of blood , tissue, or hair follicles to an individual with a high level of certainty.

DNA Fingerprint

The complete DNA of each individual is unique, with the exception of identical twins. A DNA fingerprint, therefore, is a DNA pattern that has a unique sequence such that it can be distinguished from the DNA patterns of other individuals. DNA fingerprinting is also called DNA typing.

DNA Fingerprint

The Steps to DNA Fingerprinting

The first step is to get the DNA from the specimen. The sample of DNA can be obtained from skin, hair, nails, saliva, or blood. Once the DNA is taken enzymes are used to cut it. The cuts are then made in specific spots. The enzymes are designed to cut in specific spots according to their genetic design.

How does one create a DNA fingerprint?

The scientist has to be careful in which enzyme they use because each one cuts at specific spots. Some restriction enzymes cut leaving blunt ends and some leave sticky ends. The sticky ends are preferred because they are easier to work with because they attach to other pieces of DNA easily. The blunt ends are more difficult to use because their ends do not match with other ends of other DNA. A sticky end could look like this:

5’ AGAAGAGAGAGAG TTTTCTTCTCTCTCTCTCTTT 3’

A blunt end could look like:

5’TTTTTTT AAAAAAA3’


The DNA is then sorted by gel electrophoresis. The following step is to transfer the piece of DNA to a nylon sheet and then it is soaked. This hour long process is called capillary action. After the transfer is complete the fragments are treated with ultra violet light which crosses links the DNA to the membrane. The next step is probing. The DNA is the annealed using a probe. The last thing to do is visualize the final product using an autoradiograph.


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The Uses of DNA Fingerprinting

There are several uses for DNA fingerprinting. It is not just used for personal identification by a crime scene investigator but it is also used for paternity and maternity tests. DNA fingerprinting may also be used as a system of personal identification as well as used for medical purposes in detecting and curing genetic diseases.

Personal Identification

This would be the idea of keeping everyone’s DNA on a computer as a bar code. This idea has been discussed and has been decided to be impractical and very expensive. It is very unlikely to become a system to be used. Picture identification cards and social security numbers are much more efficient and not likely to change.


Paternity and Maternity

This is also a well known use for DNA fingerprinting. This is the test used to find out who is the father of a baby or children. Every individual has a VNTR pattern which is inherited from their parents. The pattern in every individual is different but it is similar enough to reconstruct the parents VNTR. This can also be used to determine the real biological parents of an adopted child. This test can also be used to determine legal nationality. An individual should be careful when using a test like this because it can cause surprise and that may hurt some individuals.


Diagnosis and Cures for Inherited Diseases

DNA fingerprinting can also be used to detect and cure genetically inherited diseases. Using a DNA fingerprinting one can detect genetic diseases like cystic fibrosis, hemophilia, Huntington’s disease and many others. If the disease is detected at an early age it can be treated and there is a greater chance that it can be defeated. Some couples who are carriers of a disease seek out genetic counselors that can use a DNA fingerprint to help them understand the risks of them having an affected child and give them information to help them out.The fingerprints can be used by researchers to look for patterns that specific diseases have and try to figure out ways that they can cure them.


Criminal Identification and Forensics

This is a very famous method of DNA fingerprinting. This method has become so popular and well known because of the hit TV series CSI. (Crime Scene Investigation) This is a very important use of DNA fingerprinting because it can prove an individuals innocents or guilt of committing a crime. To be used a sample of DNA has to be obtained from the scene of the crime and matched with the suspect in question. The two pieces of DNA is then compared through VNTR patterns.


WHAT IS DNA TYPING ?

HOW DNA TYPING IS USED IN DETERMINING PATERNITY ?

HOW IS DNA TYPING DONE ?

OTHER USES OF DNA TYPING ?

DNA TYPING

WHAT IS DNA TYPING?

DNA typing is a procedure wherein DNA extracted from a biological sample obtained from an individual is analyzed. The DNA is processed to generate a pattern for each person that is generally termed as a “DNA profile”. This profile is unique for each person excepting that derived from identical twins.

HOW DNA TYPING IS USED IN DETERMINING PATERNITY

This analysis is based on the fact that a person possesses two DNA copies originating from the mother (maternal copy) and the father (paternal). The DNA from the mother,

the alleged father and the child are analyzed to evaluate paternity. The DNA copy contributed by the biological father should be present in the alleged father with the Probability of Paternity >95% (Case 1).

If the child possesses DNA that did not originate from the mother or the alleged father, then the alleged father cannot be the biological father of the child (Case 2).

HOW DNA TYPING IS USED IN DETERMINING PATERNITY

HOW IS DNA TYPING DONE

Sample collection or submission of evidence following a prescribed chain of custody procedure:

1. Briefing & signing of documents

2. DNA extraction

4. Automated DNA analysis


3. PCR amplification of selected Short Tandem Repeat (STR) markers

6. Release of results to all parties concerned


5. Statistical analyses of matching DNA profiles

OTHER USES OF DNA TYPINGDNA typing has broad applications.

This procedure is used in many others countries to verify the likely owner of a piece of tissue such as:

Blood

Hair

Bits of flesh

Bone

Teeth

Semen or

Any other part of the body.

OTHER USES OF DNA TYPINGClearly besides disputed parentage

cases, DNA typing also aids

in criminal investigations in identification of mass disaster

victims in verifying the identity of human

cancer cell lines in determining whether a biological

material is of human origin in studying the genetic ancestry of

human populations


Identifying DNA Evidence

Evidence Collection

Issues Concerning Contamination

Transportation and Storage

Elimination Samples


Since only a few cells can be sufficient to obtain useful DNA information to help your case, the list below identifies some common items of evidence that you may need to collect, the possible location of the DNA on the evidence, and the biological source containing the cells. Remember that just because you cannot see a stain does not mean there are not enough cells for DNA typing. Further, DNA does more than just identify the source of the sample; it can place a known individual at a crime scene, in a home, or in a room where the suspect claimed not to have been. It can refute a claim of self-defense and put a weapon in the suspect’s hand. It can change a story from an alibi to one of consent. The more officers know how to use DNA, the more powerful a tool it becomes.

EvidencePossible

Location of Source of DNA

DNA on the Evidence

baseball bat or similar weapon

handle, endsweat, skin, blood, tissue

hat, bandanna, or mask

insidesweat, hair,

dandruff

eyeglasses pieces nose or ear, lens sweat, skin

facial tissuecotton swab surface area

mucus, blood, sweat, semen,

ear wax

dirty laundry surface areablood, sweat,

semen

toothpick tips saliva

used cigarette cigarette

butt saliva

stamp or envelope licked area saliva

tape or ligatureinside/outside

surfaceskin, sweat


Evidence

Possible Location of Source of

DNA

DNA on the Evidence

bottle, can, or glass sides, mouthpiece

saliva, sweat

used condominside/outside surface

semen, vaginal or rectal cells

blanket, pillow, sheet

surface areasweat, hair, semen, urine, saliva

“through and through” bullet

outside surface blood, tissue

bite markperson’s skin or clothing

saliva

fingernail, partial fingernail

scrapingsblood, sweat, tissue


Blood and Bloodstains

If using the DNA profiling method of analysis, then blood and seminal fluid can be matched back to an individual with a high degree of probability. Currently, if using the PCR method of DNA analysis or conventional serological techniques then blood and some body fluids can be said to come from a certain population group to which the individual belongs.

EVIDENCE COLLECTION

Blood from a Person

It is always necessary to collect reference samples from suspects and victims. In the great majority of cases, these samples consist of liquid blood.Liquid blood from a person should be collected by qualified medical personnel.

The crime laboratory should be informed if the subject had recently received a blood transfusion of any kind.Two tubes of blood, about 5 mL each, should be collected in vacutainers with EDTA as anticoagulant.

EVIDENCE COLLECTION

Blood from a Person

In the case of collecting reference samples from postmortem subjects, a blood sample should be obtained from non-body cavity areas such as heart or major internal blood vessels.

Each tube should be labeled with the date, time, subject’s name, location, collector’s name,case number and exhibit number.Blood samples must be refrigerated, not frozen, and submitted to the laboratory as soon as possible.

EVIDENCE COLLECTION

Wet Bloodstains

Small objects bearing wet bloodstains should be allowed to air dry, then collected as is. An effort should be made to preserve the integrity of any bloodstain patterns during packaging and transportation.

Large objects that cannot be removed from a crime scene may have wet bloodstains on them. The wet blood should be transferred onto clean cotton cloth.

Bloodstained cotton cloth must be allowed to air dry before packaging in a paper container.

Each object and container must be properly labeled.

EVIDENCE COLLECTION

Dried Bloodstains on Removable Items

Dried bloodstains on weapons, garments and other movable objects should be collected separately by collecting the entire item.

Each item should be placed in its own (paper) container, and these should be sealed and labeled properly.

EVIDENCE COLLECTION

Dried Bloodstains on Solid, Non absorbent Surfaces of Immovable Objects

The bloodstain pattern should be documented and sketched to the extent necessary. The stain can be tape lifted or scraped off the object onto a clean piece of paper. The tape lifter or the paper with blood crust can then placed into a "druggist fold", and placed in an envelope which is sealed. Each item must be labeled properly.

EVIDENCE COLLECTION

Dried Bloodstains on Solid, Non absorbent Surfaces of Immovable Objects

If the bloodstain cannot be scraped off or the support object cannot be cut, then the bloodstain may be eluted onto a clean switch, moistened with sterilized saline or water by rubbing the cotton switch on the stained area. The switch is then allowed to dry and is placed in a paper fold packet. The packet is then placed in an envelope which is sealed, and properly labeled.

EVIDENCE COLLECTION

Dried Bloodstains on Solid, Nonabsorbent Surfaces of Immovable Objects

Always obtain a control by repeating the procedure on an adjacent but unstained area of the surface containing the bloodstain.

If the bloodstain is located on an object than can be cut, then a portion of the item containing the bloodstain can be removed by cutting with a clean, sharp instrument. Each cutting should be packaged separately and labeled accordingly. An unstained portion of the item should be collected and packaged as a control.

EVIDENCE COLLECTION

Semen and Seminal Stains

Document the semen evidence by notes, photography, videotape and sketching.

Use a clean syringe or disposable pipette to transfer liquid semen to a clean, sterile test tube.

Label the tube with the case and item number, date, time, location, and name of the collector. Keep the specimen refrigerated and submit to the laboratory as soon as possible.

EVIDENCE COLLECTION


Alternatively, liquid semen can be transferred onto clean cotton cloth by absorption. The cloth is then air dried, packaged, sealed and labeled properly.

Seminal stains on panties, clothing, bed sheets, pillows and other movable objects should be collected as is. If an article has a wet stain on it, the stain must be allowed to air dry thoroughly prior to collection of the article.

EVIDENCE COLLECTION


If the stain is on a large object that can be cut, then the stained area should be cut using a scalpel or scissors. If the stain is on immovable, nonabsorbent surfaces, then the stain should be scrapped using a clean scalpel onto clean paper, and fold the paper into a druggist fold container. Each item should be packaged separately in a clean paper container. Each item’s packaging must be properly sealed and labeled.

Packaged items should be refrigerated if possible, and submitted to the laboratory as soon as possible.

EVIDENCE COLLECTION

Seminal Evidence from Sexual Assault Victims

When dealing with sex crimes, the victim should be taken to the hospital immediately and the examination started as soon as possible. Photographs should be taken to document any injuries which the victim received. If necessary, oral, vaginal, and/or anal swabs should be taken from the victim and air dried for one hour in a moving air source as soon as possible.

EVIDENCE COLLECTION


They should be collected as soon as possible because the body begins breaking down the various components in seminal fluid through drainage, enzyme activity, pH, etc. The swabs should be air dried under a fan for at least one hour. This can either be accomplished by the doctor at the hospital, or, upon collecting the kit from the doctor, the investigator should bring it immediately to a secure place and air dry it.

EVIDENCE COLLECTION


The reason for this is that the moisture in the swabs allows microorganisms to grow which can destroy the evidentiary value of the swabs.

EVIDENCE COLLECTION

Tissue, Organ or Bone

Each item of evidence should be described in notes, and documented by photography,sketches or videotaping. This type of evidence item can be picked up with a clean pair of forceps.

Each item should be placed in a clean container without any added fixatives. Each container should be properly sealed and labeled, and stored in a freezer. Evidence should be submitted to the laboratory as soon as possible.

EVIDENCE COLLECTION


When collecting reference samples from postmortem subjects, if the body has decomposed,in addition to the blood sample, collect as many of the following specimens as possible: a portion of deep muscle tissue, certain organ tissue (e.g. heart or brain/not liver or kidney), 2-4 intact molar teeth (if identification is an issue, ensure that mouth x-rays have been taken), and a sample of compact bone (e.g. femur).

EVIDENCE COLLECTION


The specimens collected should be away from site of injury (i.e. if head injury, do not take sample of brain tissue). Immediately freeze specimens, do not place in any preservative (e.g. formalin).Collection of Urine, Saliva and Other Body Fluids follows the same rules as blood and blood stains.

EVIDENCE COLLECTION

Hair Evidence

If a root sheath is attached, then DNA analysis using PCR technology can say that this hair came from a certain percentage of the population to which the suspect belongs. If there is no root sheath, then a microscopic analysis can say that the hair has the same characteristics as the suspect's hair and is similar to his or her hair.

EVIDENCE COLLECTION

Hair Evidence

Hair found at the scene should be placed in a paper packet and then placed in an envelope. If a microscopic examination is required, then 15-20 representative hairs from the suspect must be submitted to the lab for comparison. If DNA analysis if going to be used, then a whole blood sample from the suspect must be submitted to the lab in a "Vacutainer."

EVIDENCE COLLECTION


Issues concerning contamination

Because extremely small samples of DNA can be used as evidence, greater attention to contamination issues is necessary when identifying, collecting, and preserving DNA evidence.

DNA evidence can be contaminated when DNA from another source gets mixed with DNA relevant to the case. This can happen when someone sneezes or coughs over the evidence or touches his/her mouth, nose, or other part of the face and then touches the area that may contain the DNA to be tested.



Because a new DNA technology called “PCR” replicates or copies DNA in the evidence sample, the introduction of contaminants or other unintended DNA to an evidence sample can be problematic. With such minute samples of DNA being copied, extra care must be taken to prevent contamination. If a sample of DNA is submitted for testing, the PCR process will copy.



To avoid contamination of evidence that may contain DNA, always take the following precautions:

Wear gloves. Change them often.

Use disposable instruments or clean them thoroughly before and after handling each sample.

Avoid touching the area where you believe

DNA may exist.



Avoid talking, sneezing, and coughing

Avoid touching your face, nose, and mouth

when collecting and packaging evidence.

Air-dry evidence thoroughly before packaging

Put evidence into new paper bags or packaging envelopes, not into plastic bags. Do not use staples.

whatever DNA is present in the sample; it cannot distinguish between a suspect’s DNA and DNA from another source.

Care should be taken to ensure that biological evidence is not contaminated during its collection:

• To avoid contamination, do not allow one evidence stain to come into contact with other biological samples.

• Do not talk or cough over biological evidence stains. Do not handle samples without using clean gloves.

• Each individual stain should be collected separately. Do not collect or package two separate stains together.



• Do not allow evidence samples to come into contact with any surface that contains residue from another biological sample (e.g. dirty tweezers, bloodstained glove, contaminated work surface).

• Use tweezers that have smooth, easy-to-clean working surfaces.

• Tools (e.g. tweezers, scissors) can be cleaned by thoroughly rinsing with a stream of distilled water and thoroughly drying with paper tissue. Repeat this process twice before using tool to manipulate another sample.



Package all biological evidence in paper bags or envelopes (do not use plastic). The packaging of biological evidence in plastic or airtight containers must always be avoided, because the accumulation of residual moisture could contribute to the growth of DNA-destroying bacteria and fungi.

• Allow stains to air dry as much as possible before placing in paper bag or envelope.

• Package the “unstained control” separately from the evidence stain.



• Package different evidence items in separate paper containers.

• Ensure that the paper container is large enough to allow air circulation around evidence item.

• Clean paper can be placed on (or in) a bloodstained garment and the garment folded so that the paper prevents contact between different stains. Ensure that while items are drying that the stain pattern(s) are not altered or the stain(s) cross-contaminated with other wet stain(s).



Do not freeze metal or glass evidence items with blood or other body fluid stains.

Submit these items to the laboratory as soon as possible.

• Tape seal, initial and date all paper bags or envelopes.




When transporting and storing evidence that may contain DNA, it is important to:

Keep the evidence dry and at room temperature.

Once the evidence has been secured in paper bags or envelopes, it should be sealed, labeled, and transported in a way that ensures proper identification of where it was found and proper chain of custody.



When transporting and storing evidence that may contain DNA, it is important to:

Never place evidence that may contain DNA in plastic bags “because plastic bags will retain damaging moisture.”

Direct sunlight and warmer conditions also may be harmful to DNA, so avoid keeping evidence in places that may get hot, such as a room or police car without air conditioning.


ELIMINATION SAMPLES

AS WITH FINGERPRINTS, THE EFFECTIVE USE OF DNA MAY REQUIRE THE COLLECTION AND ANALYSIS OF ELIMINATION SAMPLES. IT OFTEN IS NECESSARY TO USE ELIMINATION SAMPLES TO DETERMINE WHETHER THE EVIDENCE COMES FROM THE SUSPECT OR FROM SOMEONE ELSE. AN OFFICER MUST THINK AHEAD TO THE TIME OF TRIAL AND POSSIBLE DEFENSES WHILE STILL AT THE CRIME SCENE. FOR EXAMPLE, IN THE CASE OF A RESIDENTIAL BURGLARY WHERE THE SUSPECT MAY HAVE DRUNK A GLASS OF WATER AT THE CRIME SCENE, AN OFFICER SHOULD IDENTIFY APPROPRIATE PEOPLE, SUCH AS HOUSEHOLD MEMBERS, FOR FUTURE ELIMINATION SAMPLE TESTING.


ELIMINATION SAMPLES

THESE SAMPLES MAY BE NEEDED FOR COMPARISON WITH THE SALIVA FOUND ON THE GLASS TO DETERMINE WHETHER THE SALIVA IS VALUABLE EVIDENCE. IN HOMICIDE CASES, BE SURE TO COLLECT THE VICTIM’S DNA FROM THE MEDICAL EXAMINER AT THE AUTOPSY, EVEN IF THE BODY IS BADLY DECOMPOSED. THIS MAY SERVE TO IDENTIFY AN UNKNOWN VICTIM OR DISTINGUISH BETWEEN THE VICTIM’S DNA AND OTHER DNA FOUND AT THE CRIME SCENE.


ELIMINATION SAMPLES

WHEN INVESTIGATING RAPE CASES, IT MAY BE NECESSARY TO COLLECT AND ANALYZE THE DNA OF THE VICTIM’S RECENT CONSENSUAL PARTNERS, IF ANY, TO ELIMINATE THEM AS POTENTIAL CONTRIBUTORS OF DNA SUSPECTED TO BE FROM THE PERPETRATOR. IF THIS IS NECESSARY, IT IS IMPORTANT TO APPROACH THE VICTIM WITH EXTREME SENSITIVITY AND PROVIDE A FULL EXPLANATION OF WHY THE REQUEST IS BEING MADE. WHEN POSSIBLE, THE HELP OF A QUALIFIED VICTIM ADVOCATE SHOULD BE ENLISTED FOR ASSISTANCE.


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