blood and blood stains n.
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  2. Chem-195 H

  3. IMPORTANCE OF THE STUDY OF BLOOD • As circumstantial or corroborative evidence against or in favor of the culprit • For disputed parentage • Determination of the cause of death and the length of time the victim survived the attack. Chem-195 H

  4. IMPORTANCE OF THE STUDY OF BLOOD cont… • Determination of the direction of escape of the victim or the assailant. • Determination of the origin of the flow of blood. • Determination of the approximate time the crime was committed. Chem-195 H

  5. SOME CHARACTERISTICS OF BLOOD: • The circulating tissue of the body • 1 cc of blood: 5,000,000 red cells. • Man of average size: about 6 quarts of blood • Made up of FORMED ELEMENTS {a. RBC (Erythrocytes) b. WBC (Leucocytes) c. PLATELETS (Thrombocytes)} and PLASMA (liquid portion of blood; composing about 65% of the total blood volume) Chem-195 H

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  7. SOME CHARACTERISTICS OF BLOOD: cont… • Serum – • a straw-yellowish liquid that can be seen when blood is allowed to clot. Chem-195 H

  8. PROBLEMS IN THE STUDY OF BLOOD: • Where blood has to be searched for. • Collection, preservation and transportation of specimen suspected to contain blood. • Does the stain contain blood or another substance? Chem-195 H

  9. PROBLEMS IN THE STUDY OF BLOOD: cont… • If the stain is that of blood, is it human or animal? • If the stain is of human blood, did it come from the victim, the accused or from other persons? Chem-195 H

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  13. Whether Stain Is of Blood or Another Substance • Preliminary Test • Presumptive or Color Test) – a positive result is not conclusive that the stain is blood but a negative result is conclusive that the stain is not blood. • REASON: Other substances may yield the same reaction as blood. This includes: saliva, nasal secretion, plant juices, formalin, etc. Chem-195 H

  14. Whether Stain Is of Blood or Another Substance cont… B. Confirmatory Tests – • The actual proof that a stain is blood consists in establishing the presence of characteristic blood pigment, hemoglobin or one of its derivatives. • The 3 Confirmatory Tests commonly employed are Teichmann, Takayama and Wagenhaar Tests. They are designed to show the presence of hemoglobin in a suspected bloodstain by the appearance of specific crystals observed under a microscope. Chem-195 H

  15. Preliminary Tests for the Presence of Blood Chem-195 H

  16. Preliminary Tests for the Presence of Blood cont… Chem-195 H

  17. Preliminary Tests for the Presence of Blood cont… Chem-195 H

  18. Preliminary Tests for the Presence of Blood cont… Chem-195 H

  19. Preliminary Tests for the Presence of Blood cont… Chem-195 H

  20. Confirmatory Tests • Teichmann or Haemin Crystal Test – Dark brown rhombic crystals arranged singly or in clusters • Takayama or Haemochromogen Crystal Test Large rhombic crystals of salmon-pink color arranged in clusters, sheaves and other forms Chem-195 H

  21. Confirmatory Tests cont… • Wagenhaar Test or Acetone-Haematin – Small dark, circular crystals Chem-195 H

  22. Whether Blood Is of Human or Animal Precipitin Test (human antiserum) – The formation of gray precipitation ring at the interface of the two layers within 20 minutes indicates that the stain is human blood. Chem-195 H

  23. ORIGIN OF BLOOD This is determined by blood grouping. A-B-O system, which was discovered by Karl Landsteiner in early 1900s, was the first system of blood grouping. Chem-195 H

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  29. Intoxication cont… • A blood also extracted from individuals suspected to be intoxicated are examined to determine whether they are under the influence of alcohol or not, at the time of the extraction. • The percentage of alcohol obtained from the blood are examined and interpreted by the medico-legal officer to determine the percentage of alcohol level in the blood. Chem-195 H

  30. THE PERISHABLE NATURE OF BLOOD • Blood is type of evidence, which undergoes a rapid change in its character with the passage of time. • Furthermore, blood offers little resistance to decomposition, especially when exposed to certain conditions and influences, which if prolonged, will cause the specimen to lose its identity. Chem-195 H

  31. THE FRESH NATURE OF BLOOD cont… • It is therefore extremely important that blood samples be sent to the laboratory as soon as possible after their discovery or scientifically preserve. • Prior to the general search of the crime scene, the floor should be examined carefully in order to minimize the danger of loss or destruction caused by being walked upon by persons otherwise engaged in the investigation. Chem-195 H

  32. GUIDE TO PHYSICAL EVIDENCE COLLECTION Amount Desired Specimen – Liquid Known Samples Standard – One tube each (sterile) 5cc-10cc blood only. No preservatives. Send By – Registered mail or equivalent Chem-195 H

  33. SPECIMEN – LIQUID KNOWN SAMPLES Identification • Outside test tube: Use adhesive tape. Name of donor, date taken, doctor’s name, investigator’s name or initials. • Wrapping and Packing: Wrap in cotton/soft paper. • Place in mailing tube or suitable strong mailing carton. Chem-195 H

  34. SPECIMEN – LIQUID KNOWN SAMPLES cont… • Remarks – submit immediately. Don’t hold awaiting additional items for comparison. • Do not freeze, keep refrigerated until mailing. • Do not add refrigerants and/or dry ice to sample during transit. • Label “Fragile.” Chem-195 H

  35. SPECIMEN – SMALL QUANTITIES: a. Liquid Questioned Samples cont… Remarks – If unable to expeditiously furnish sample: Dry on nonporous surface, scrape off or collect (use eye droppers or clean spoon), transfer to nonporous surface or absorb in sterile gauze and let it dry. Chem-195 H

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