THE USE OF DNA TECHNOLOGY IN CRIMINAL INVESTIGATION IN TANZANIA. BY G. MACHUVE FORENSIC DNA UNIT GCLA
Applications of DNA technology <ul><li>In criminal investigations scientists utilize DNA profile of a charged person and c...
TYPES OF SAMPLES RECEIVED <ul><li>Biological samples such as blood, buccal swab, semen, sweat in clothes, hair and saliva ...
EVIDENCE SAMPLES AT CRIME SCENE LIKELY TO CONTAIN DNA  Saliva  Edge of toothpicks, depris in toothbrushes Toothpicks, toot...
Cont.. Sweat & blood Handles, trigger and burrel  Guns,  8 saliva Saliva on envelope seal Stamps, envelopes 7 Blood, semen...
Cont… Feaces, urine Toilet bowls, seats and floor Toilets  13 Blood & tissues Kidney, liver, intestines, bones Body parts ...
Responsibility of crime investigators handling DNA samples;   <ul><ul><li>The investigative officer must accept the respon...
Responsibility of crime investigators handling DNA samples ….. <ul><ul><li>The point is that the evidence samples should n...
Responsibility of crime investigators handling DNA samples ….. <ul><li>The DNA Scientist has to work with what has been su...
GUIDELINES FOR INVESTIGATING OFFICERS   <ul><li>Careful observation of the crime scene prior to handling any evidence samp...
GUIDELINES FOR INVESTIGATING OFFICERS <ul><li>Isolate/seal the crime scene using police warning tapes until forensic exper...
GUIDELINES FOR INVESTIGATING OFFICERS <ul><li>Collect all possible evidence (materials) that may link a suspect to a crime...
GUIDELINES Cont… <ul><li>Appropriate sampling kits should be utilized in collecting evidence samples </li></ul><ul><li>Saf...
GUIDELINES Cont… <ul><li>Store the gathered information either in writing or computer etc… </li></ul><ul><li>Usually blood...
Storage and securing of evidence samples;   <ul><li>Evidence samples should be stored according to the case file </li></ul...
Storage and securing of evidence samples  cont….. <ul><li>Buccal swab evidence samples should be dried out and stored at r...
Handling of Raw blood (5-10mls); <ul><li>A white sterile cotton cloth should be used to soak-up the splattered blood at th...
Handling of Dried Blood;   <ul><li>Scrap off the dried out blood using a clean scalpel and transfer it to a clean paper en...
Packaging and labeling of evidence samples;   <ul><li>Evidence samples must be out of harm's way </li></ul><ul><li>The typ...
Transportation of DNA evidence samples to DNA profiling laboratories; <ul><li>DNA evidence samples have to be properly sea...
Information which should accompany the samples <ul><ul><li>The type and amount of evidence samples </li></ul></ul><ul><ul>...
Information which should accompany the samples cont… <ul><ul><li>The name of the deliverer of the samples </li></ul></ul><...
Conditions under which evidence samples are rejected by DNA laboratories include ;   <ul><li>Missing labels on evidence sa...
Conditions under which evidence samples are rejected by DNA laboratories include ; <ul><li>Dirty packaging of evidence sam...
DNA Analysis Reports released 2005/2006   - - 59 Rape  27 73 159 Murder  60 40 250 Paternity  Exclusive (%) Inclusive (%) ...
DNA Analysis Reports released 2005/2006   cont… 2 Male 1 3 Sex identification  Female  No. of samples analyzed
FACTORS WHICH MAY AFFECT DNA EVIDENCE   <ul><li>There are several environmental factors that can affect DNA’s integrity  <...
FACTORS WHICH MAY AFFECT DNA EVIDENCE  cont… <ul><li>cross contamination while handling evidence samples;  </li></ul><ul><...
CONCLUDING REMARKS <ul><li>Crime scene investigators should possess the necessary knowledge on collection, packaging and t...
<ul><li>THANK YOU FOR YOUR TIME  </li></ul>
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Dna theory 3

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  • Therefore, if human DNA samples are found at a crime scene, a DNA profiling test can be carried out to determine whether a suspect could be a possible source of a sample. Consequently, DNA evidence has already been put to use to implicate criminals in serious offenses such as; murder case where the victim has suffered multiple stab wounds and a suspect subsequently apprehended in possession of blood stained clothing. The DNA profile from the blood stained clothing could be compared with a sample from the victim. rape case whereby a woman has scratched her assailant and gets skin cells trapped under her fingernails. The DNA profile from the skin cells could be compared with a blood or saliva sample from a suspect. parentage case where a father has disputed his relationship to a child. The DNA profile of child could be compared with a blood or saliva sample from father. mass disaster where victims have lost their recognition in a plane crash. DNA profiles from the remains could be compared with blood or saliva samples from their close relatives.
  • The DNA scientist has to work with what he receives and the value of his work/ results depends on the quality of the material/sample submitted to him/her This is crucial for so few of us do actually follow sample management procedures when slight mismanagement errors occur and impact the integrity of DNA analytical results. There are several things which the officer investigating a crime, must remember, if the team (investigators and DNA scientists) is to be fully effective;
  • The following tables summarize the total number of cases received for DNA analysis test in the year 2005/06. The DNA samples analyzed were of both civil and criminal categories, with the majority being civil (paternity).
  • Not wearing appropriate attires – e.g., gloves Stepping on blood at the crime scene Washing down of evidence located on toilets or hand wash basins – rape cases Smoking of cigarettes at the crime scene Spitting Combing of hair Nose blowing (Sneezing) Handling of samples with oily hands
  • Dna theory 3

    1. 1. THE USE OF DNA TECHNOLOGY IN CRIMINAL INVESTIGATION IN TANZANIA. BY G. MACHUVE FORENSIC DNA UNIT GCLA
    2. 2. Applications of DNA technology <ul><li>In criminal investigations scientists utilize DNA profile of a charged person and compare it against DNA (human biological samples) from the crime scene. </li></ul><ul><li>For instance; </li></ul><ul><ul><li>Murder case </li></ul></ul><ul><ul><li>Rape cases </li></ul></ul><ul><ul><li>Paternity cases </li></ul></ul><ul><ul><li>Mass disaster – plane crash, fire accidents, massacre, </li></ul></ul>
    3. 3. TYPES OF SAMPLES RECEIVED <ul><li>Biological samples such as blood, buccal swab, semen, sweat in clothes, hair and saliva are usually received and used to extract/obtained sufficient quantities of DNA. </li></ul>
    4. 4. EVIDENCE SAMPLES AT CRIME SCENE LIKELY TO CONTAIN DNA Saliva Edge of toothpicks, depris in toothbrushes Toothpicks, toothbrush 4 Sweat, skin Nose bridge & earlobe Spectacles/glasses 3 Sweat, hair, dandruff Inner lining A cap 2 Sweat,blood & skin Handles and blades of knives Knives, 1 Source of DNA Place where DNA can be found Exhibit S/N
    5. 5. Cont.. Sweat & blood Handles, trigger and burrel Guns, 8 saliva Saliva on envelope seal Stamps, envelopes 7 Blood, semen, sweat, dandruff, hair underpants, shirts, trousers, dresses, sheets, socks, Clothes 9 Saliva, sweat Rims and edges of bottles, cans, bowls, cups Bottle, glass, cans, bowls, cups 6 Saliva Cigarette butts, cigar pipes’ mouth piece Cigarette, cigar pipes 5
    6. 6. Cont… Feaces, urine Toilet bowls, seats and floor Toilets 13 Blood & tissues Kidney, liver, intestines, bones Body parts 12 Sweat, blood, hair, fingerprints & saliva Car seats, seat belts, steering wheel, tires, window glass, door knobs, buttons, rear mirrors etc… Vehicles 11 Sweat & blood Foot wear, socks Foot wear 10
    7. 7. Responsibility of crime investigators handling DNA samples; <ul><ul><li>The investigative officer must accept the responsibility for seeing that the right types of samples are received to the DNA laboratory </li></ul></ul><ul><ul><li>The point is that the evidence samples should not be exposed to any possibility of destruction, mishandling, contamination, and any other conceivable catastrophe that can be brought on by human or natural error. </li></ul></ul>
    8. 8. Responsibility of crime investigators handling DNA samples ….. <ul><ul><li>The point is that the evidence samples should not be exposed to any possibility of destruction, mishandling, contamination, and any other conceivable catastrophe that can be brought on by human or natural error. </li></ul></ul>
    9. 9. Responsibility of crime investigators handling DNA samples ….. <ul><li>The DNA Scientist has to work with what has been submitted to the Laboratory ad the results will depend on the quality of the sample/evidence submitted. </li></ul><ul><li>The investigating officer at the crime scene should observe the following guidelines: </li></ul>
    10. 10. GUIDELINES FOR INVESTIGATING OFFICERS <ul><li>Careful observation of the crime scene prior to handling any evidence samples must be followed </li></ul><ul><li>Store crime scene memory in the form of photographs or drawings </li></ul>
    11. 11. GUIDELINES FOR INVESTIGATING OFFICERS <ul><li>Isolate/seal the crime scene using police warning tapes until forensic experts arrive </li></ul><ul><li>Collecting of evidence samples should be performed by either qualified personnel (crime scene examiner) or Government Chemist laboratory experts </li></ul>
    12. 12. GUIDELINES FOR INVESTIGATING OFFICERS <ul><li>Collect all possible evidence (materials) that may link a suspect to a crime scene. </li></ul><ul><li>Store gathered information in writing (e.g. note books etc). </li></ul><ul><li>Use appropriate sampling kits in collecting DNA evidence samples. </li></ul>
    13. 13. GUIDELINES Cont… <ul><li>Appropriate sampling kits should be utilized in collecting evidence samples </li></ul><ul><li>Safety and occupational health guidelines such as the wearing of gloves, shoes and masks should be observed </li></ul><ul><li>Collect all the possible evidence (materials) that may link a suspect to a crime scene </li></ul>
    14. 14. GUIDELINES Cont… <ul><li>Store the gathered information either in writing or computer etc… </li></ul><ul><li>Usually blood or buccal swab samples are taken from the suspected perpetrators so as to perform DNA analysis test for profile matching to crime scene samples </li></ul>
    15. 15. Storage and securing of evidence samples; <ul><li>Evidence samples should be stored according to the case file </li></ul><ul><li>Evidence samples should be stored separately and appropriately labeled to avoid contamination of samples </li></ul><ul><li>Evidence samples should then be locked away in a secured room </li></ul>
    16. 16. Storage and securing of evidence samples cont….. <ul><li>Buccal swab evidence samples should be dried out and stored at room temperature whilst raw blood evidence samples should be refrigerated. This is crucial as DNA samples last for an indefinite period of time when preserved properly. </li></ul>
    17. 17. Handling of Raw blood (5-10mls); <ul><li>A white sterile cotton cloth should be used to soak-up the splattered blood at the crime scene. This cloth should then be air dried and placed in a clean paper envelope. </li></ul><ul><li>Blood samples should be packaged in a sterile dry glass bottle mixed with anticoagulant such as sodium fluoride. </li></ul>
    18. 18. Handling of Dried Blood; <ul><li>Scrap off the dried out blood using a clean scalpel and transfer it to a clean paper envelope. </li></ul><ul><li>Alternatively, a white sterile cloth moistened with distilled water can be used to wipe off the dried blood and then air dried and stored in a clean paper envelope. </li></ul>
    19. 19. Packaging and labeling of evidence samples; <ul><li>Evidence samples must be out of harm's way </li></ul><ul><li>The type of evidence samples must be indicated </li></ul><ul><li>There should not be more than one label </li></ul><ul><li>Permanent (water insoluble) marker pens should be used in labeling samples </li></ul>
    20. 20. Transportation of DNA evidence samples to DNA profiling laboratories; <ul><li>DNA evidence samples have to be properly sealed/ packaged and labeled so as to prevent them from being tempered with. </li></ul><ul><li>The DNA samples must be accompanied with appropriate authoritative forms (e.g., PF 180) </li></ul>
    21. 21. Information which should accompany the samples <ul><ul><li>The type and amount of evidence samples </li></ul></ul><ul><ul><li>The origin of the sample </li></ul></ul><ul><ul><li>The type of crime committed </li></ul></ul><ul><ul><li>The type of testing requested </li></ul></ul><ul><ul><li>The name and signature of the head of investigation </li></ul></ul>
    22. 22. Information which should accompany the samples cont… <ul><ul><li>The name of the deliverer of the samples </li></ul></ul><ul><ul><li>DNA samples for parentage identification must have referrals from court orders, registered advocates or Social welfare. </li></ul></ul>
    23. 23. Conditions under which evidence samples are rejected by DNA laboratories include ; <ul><li>Missing labels on evidence samples </li></ul><ul><li>Absence of authoritative forms, PF180, permitting the legal handling of evidence samples </li></ul><ul><li>Unlabelled or destroyed labels on evidence samples </li></ul><ul><li>Evidence samples not listed in the. PF. 180. </li></ul><ul><li>Plastic packaging of evidence samples is not allowed as this may cause degradation of the biological material of interest </li></ul>
    24. 24. Conditions under which evidence samples are rejected by DNA laboratories include ; <ul><li>Dirty packaging of evidence samples </li></ul><ul><li>Unpreserved evidence samples </li></ul><ul><li>More than one label (single labeling scheme) on evidence samples </li></ul>
    25. 25. DNA Analysis Reports released 2005/2006 - - 59 Rape 27 73 159 Murder 60 40 250 Paternity Exclusive (%) Inclusive (%) No. of samples analyzed Types of cases
    26. 26. DNA Analysis Reports released 2005/2006 cont… 2 Male 1 3 Sex identification Female No. of samples analyzed
    27. 27. FACTORS WHICH MAY AFFECT DNA EVIDENCE <ul><li>There are several environmental factors that can affect DNA’s integrity </li></ul><ul><ul><li>Heat, sunlight, moisture, bacteria and mold. </li></ul></ul><ul><ul><li>Therefore, not all DNA evidence samples can be useful for DNA tests </li></ul></ul>
    28. 28. FACTORS WHICH MAY AFFECT DNA EVIDENCE cont… <ul><li>cross contamination while handling evidence samples; </li></ul><ul><ul><li>Not wearing appropriate attires – e.g., gloves </li></ul></ul><ul><ul><li>Stepping on blood at the crime scene </li></ul></ul><ul><ul><li>Washing down of evidence located on toilets or hand wash basins – rape cases </li></ul></ul>
    29. 29. CONCLUDING REMARKS <ul><li>Crime scene investigators should possess the necessary knowledge on collection, packaging and transportation of DNA evidence samples. </li></ul><ul><li>Confidentiality of DNA evidence samples should be adhered. </li></ul>
    30. 30. <ul><li>THANK YOU FOR YOUR TIME </li></ul>

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