Forensic Serology: Blood

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Forensic Serology Blood

• Written By Alice Yang
• Period 7
• Instructor Mary Villani

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The Forensic Serologist

• The forensic serologist studies body
• fluids such as semen, saliva, and blood
• mainly for identification purposes.
• Role(s)
• Establishing type and characteristics of
• blood
• Blood testing
• Examination of bloodstains
• DNA typing
• Preparation of court testimony
• evidence

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Blood Evidence

• Blood is the most well-known and
• significant evidence in the modern
• criminal justice system.
• Blood evidence is important to the forensic
• investigator because
• It can link a victim to a suspect
• (Locards Exchange Principle
• Bloodstain patterns can reveal a great
• deal about position and movement during
• the crime
• It has managed to destroy self-defense
• arguments of suspects

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Forensic Value of Blood

• In forensic science, blood has always been
• considered class evidence. However,
• individualized blood evidence is possible
• in the near future. In fact, in some cases,
• forensic serologists were able to link a
• single perpetrator to a bloodstain with
• strong probability estimates.

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Nature of Blood General Characteristics

• Blood is a slightly alkaline fluid that
• circulates throughout our bodies,
• nourishing our cells, and transporting
• oxygen and waste. The fluid portion of
• blood consists of plasma and serum, while
• the non-fluid portion consists of red blood
• cells.
• Blood is composed of
• Water
• Cells
• Enzymes
• Proteins
• Other inorganic substances

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Nature of Blood Serum

• Serum is characterized by its yellow hue,
• and contains white blood cells and
• platelets. Forensic analysts are able to
• determine the freshness of a blood sample
• by examining serum because it clots
• several minutes after exposure to air. A
• centrifuge can be used to separate the
• clotted material from the serum portion. In
• addition, serum contains antibodies ,
• proteins floating in blood fluid, which have
• significant forensic implications.

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Nature of Blood Red Blood Cells

• Red blood cells, the most prevalent blood
• cells in the human body, are the primary
• means of delivering oxygen from the lungs
• to the bodys tissues via the blood. For red
• blood cells, the forensic analyst
• searches for smaller chemical substances
• residing on their surfaces, such as
• antigens , which also tend to have
• important forensic implications.

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Blood Grouping

• The A-B-O system of blood typing was
• discovered in 1901 by Dr. Karl Landsteiner.
• During the late 1930s, a series of
• antigen-antibody reactions were
• discovered in blood, the most common
• ones being ABH, MN, Rh, and Gm. There are
• more than 256 antigens, and twenty-three
• blood group systems based on association
• with these antigens. A fundamental
• principle of serology is that for every
• antigen, there exists a specific antibody. In
• fact, all blood groups are defined by the
• antigens on their red blood cells and the
• antibodies in their serum.

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Blood Typing

• Blood typing requires two antiserums
• anti-A and anti-B. By inserting a droplet of
• these antiserums in samples of blood, one
• can determine which samples maintain a
• normal appearance and which samples
• become clotted, or agglutinated, under
• microscopic examination. Type-A blood will
• be agglutinated by anti-A serum Type-B
• blood will be agglutinated by anti-B serum
• Type-AB blood by both and Type-O blood by
• neither.

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Rh Factor

• Blood can also be categorized using the Rh
• (Rhesus disease) factor.  If an individual
• has a positive Rh factor, this means that
• his/her blood contains a protein that is
• also found in Rhesus monkeys. 
• Approximately 85 of the population has a
• positive Rh factor, and doctors are trained
• to monitor closely any woman who is Rh
• negative and becomes pregnant. The Rh
• factor, like other antigens, can be found on
• the surface of red blood cells. 

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Individualization of Blood

• The potential for the individualization of
• blood is based on the typing of proteins and
• enzymes. Blood proteins and enzymes have
• the quality of being polymorphisms or
• iso-enzymes , which means they exist in
• several forms and variants. Most people
• are familiar with at least one common
• polymorphism in blood Hb, which causes
• sickle-cell anemia.

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Secretors

• In 1925, a blood-related discovery valuable
• to forensic science was made.
• Approximately eighty-percent of the human
• population was found to be "secretors,"
• individuals whose specific types of
• antigens, proteins, antibodies, and
• enzymes characteristic of their blood can
• be found in other bodily fluids and
• tissues.  In the case of a secretor,
• investigators can conclude the blood type
• by examining the saliva, teardrops, skin
• tissue, urine, or semen. In a rape case, for
• example, where the perpetrator is a
• secretor, potential suspects can be
• narrowed down through blood type
• analysis.

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Bloodstain Analysis The General Questions

• During bloodstain analysis, the forensic
• investigator uses these five specific
• questions as guidelines for determining
• the nature of a crime.
• 1. Is the sample blood?
• 2. Is the sample animal blood?
• 3. If the sample is animal blood, from what
• species did it come from?
• 4. If the sample is human blood, what type
• is it?
• 5. Can the sex, age, and race of the source
• of blood be determined?

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Bloodstain Analysis Blood or not?

• To determine whether or not blood is
• present at a crime scene, forensic
• investigators use color or crystalline tests.
• In the past, police investigators were
• trusted to verify the presence or absence of
• blood, but Miller v. Pate (1967) enforced that
• physical tests should be completed in the
• search for blood. The Benzidine test was
• widely implemented until it was discovered
• to be a known carcinogen. The current
• Kastle-Meyer test, which uses the
• chemical, phenolphthalein, operates on the
• fact that when phenolphthalein comes in
• contact with hemoglobin, it releases
• peroxidase enzymes that cause a bright
• pink color to appear. 

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Bloodstain Analysis Blood or not?

• In order to detect invisible bloodstains,
• forensic investigators use the luminol test.
• Luminol, a chemical sprayed on carpets
• and furniture, reveals a slightly
• phosphorescent light in the dark where
• bloodstains (and other stains) are present.
• Long-dried blood has a tendency to
• crystallize, or can be made to crystallize
• with various saline-acid mixtures. The
• names of various crystal tests are the
• Teichman test , the Takayama test , and
• Wagenhaar test. 

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Bloodstain AnalysisAnimal Blood?

• To determine whether blood at the crime
• scene originated from an animal, forensic
• investigators use antiserum or gel tests.
• Establishing whether or not blood is animal
• blood is significant because any possibility
• of an injury to the household pet, caused by
• a perpetrator or another animal, must be
• eliminated. Pets generally spread human
• bloodstains throughout the crime scene,
• but the pet can be a victim, perpetrator, or
• witness (through the cross transfer of
• evidence between the animals DNA and the
• perpetrator). Veterinary forensics may be a
• necessary unit if pets are involved in the
• crime.

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Bloodstain AnalysisAnimal Blood?

• To determine whether blood is animal or
• human in origin, the precipitin test is
• conducted. This process involves injecting
• an animal, usually a rabbit, with human
• blood. The rabbit's body creates
• anti-human antibodies, which are then
• extracted from the rabbit's serum. If this
• antiserum is then placed on a sample from
• the crime scene, and the blood displays
• clotting, the forensic investigator can
• conclude that the blood is human blood.
• The same procedure of creating and
• extracting antiserum can be applied to
• every known animal.

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Bloodstain AnalysisHuman Blood?

• To confirm whether blood is human in
• origin, the forensic investigator must first
• determine that he has an adequate and
• quality blood sample. A blood sample that
• meets these requirements can undergo
• direct typing using the A-B-O system. If
• severely dried stains are uncovered,
• indirect typing should be completed using
• techniques such as the absorption-elution
• test. During this test, the forensic scientist
• adds compatible antiserum antibodies to a
• sample, heats the sample to break the
• antibody-antigen bonds, and finally inserts
• known red blood cells from standard blood
• groups to see what coagulates.

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Bloodstain AnalysisAge, Sex, Race

• To estimate the age, sex, and race using
• blood found at the crime scene, the
• forensic scientist uses various color and
• nitrate tests, and applies heredity
• principles to his tests. Unfortunately, no
• exact determinations are possible.
• However, clotting and crystallization can
• help approximate age, testosterone and
• chromosome testing can help determine
• sex, and certain racial genetic markers
• involving protein and enzyme tests can
• help establish race.

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Blood Crime SceneWet vs. Dry Blood

• Wet blood is more significant than dried
• blood because the forensic scientist can
• perform more tests in order to gain insight
• to the happenings of the crime. For
• example, alcohol and drug content can be
• determined from wet blood only. Blood
• begins to dry after three to five minutes of
• exposure to air. As it dries, it changes color
• from a deep red towards brown and black.
• Blood can be categorized into pools, drops,
• smears, or crusts.

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Projection of Blood

• Forensic investigators can determine how
• blood was projected from the body by
• examining factors such as
• Type of injuries
• The order in which the wounds were received
• Whose blood is present
• The type of weapon that caused the injuries
• Whether the victim was in motion or lying still
  when the injury was inflicted
• Whether the victim was moved after the injury was
  inflicted
• How far the blood drops fell before hitting the
  surface where they were found.

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Blood Crime SceneCategories of Blood Patterns

• Pools of blood have evidentiary value in
• collecting a wet sample. Drops of blood can
• reveal the height and angle from which the
• blood fell onto the surface. According to
• forensic scientists, the blood spatter
• analysis claims that blood which falls
• perpendicular to the floor from a distance
• of zero to two feet would create a circular
• drop with slightly frayed edges. Drops from
• a higher distance would have more distinct
• tendrils extending off the edges.

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Blood Crime SceneCategories of Blood Patterns

• A blood smear on the wall or floor can
• indicate the direction of force of the
• blow.  The direction of force is always in the
• direction towards the tail, or smaller end, of
• the smear. In other words, the largest area
• of the smear is the point of origin. Blood
• crusts must be tested with crystalline
• techniques to verify that they are actually
• blood. Refrigerated red blood cells have a
• shelf life of about forty-two days, and the
• serum containing white blood cells can be
• refrigerated much longer, almost up to a
• year.  DNA can be extracted from blood (if
• white blood cells which always contain a
• nucleus are present), and also from sperm,
• bone marrow, tooth pulp, and hair roots.

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Blood DNA Testing

• Blood is used in DNA testing, as shown by
• the following steps
• 1. Blood samples are collected from the
• victim, defendant, and crime scene.
• 2. White blood cells are separated from red
• blood cells.
• 3. DNA is extracted from the nuclei of white
• blood cells.
• 4. A restrictive enzyme is used to cut
• fragments of the DNA strand.
• 5. DNA fragments are put into a bed of gel
• with electrodes at either end.
• 6. Electric current sorts DNA fragments by
• length.
• 7. An absorbent blotter soaks up the imprint it
• is radioactively treated, and an X-ray
• photograph, called an autoradiograph, is
• produced.

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Blood Crime Scene

• Regardless of what type of analysis is used
• on the blood at the crime scene, care must
• be taken to handle it properly and to
• prevent putrefaction.  Photographs and
• notes should be taken before any blood is
• lifted.  Samples should not be exposed to
• heat, moisture, or bacterial contamination,
• because these factors can shorten the
• survival time of proteins, enzymes, and
• antigens.  Delays in bringing samples to the
• lab must be avoided at all cost, because it
• can diminish evidential value.

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Court Significance

• Experts in bloodstain examination are
• usually law enforcement personnel. In
• certain jurisdictions, a police investigator
• or blood specialist may testify on the core
• issue because blood evidence is usually a
• vital aspect of the crime scene.
• An expert in bloodstain examination has
• Completed specialized training
• Conducted a sufficient number of
• examinations
• Accumulated enough reference patterns
• to reinforce an argument

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References

• Data
• http//www.crimelibrary.com/criminal_mind/forensic
  s/serology/3.html
• http//www.policensw.com/info/forensic/forensic6a.
  html
• Images
• Slide 1 http//www.fbi.gov/hq/lab/fsc/backissu/oc
  t2004/images/2004_10/kienker02.jpg
• Slide 2
• http//www.separationsnow.com/FCKeditor/UserFiles/
  Image/sepNOW_ezines_2006/0602
• _dep.jpg
• Slide 3 http//www.fdle.state.fl.us/CrimeLab/imag
  es/dna20feathered.jpg
• Slide 4
• http//www.ecmagazine.net/Winter0607/winter06webph
  otos/Blood20Serum.
• Pg
• Slide 5
• http//www.freewebs.com/soaring_sphincter_travel_a
  gency/red20blood20cells.bmp

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References

• Slide 6 http//www.antibody.com/images/CD4.gif
• Slide 7 http//web.indstate.edu/thcme/PSP/blood/b
  ld-type.jpg
• Slide 8 http//www.dnr.state.md.us/education/hor
  seshoecrab/2005art/testtube2.jpg
• Slide 9 http//science.uwe.ac.uk/projectshowcase/
  blood_cells20copy.JPG
• Slide 10 http//www.ljmu.ac.uk/MKG_Global_Images/
  testtube_blood.jpg
• Slide 11 http//www.ronsmithandassociates.com/blo
  odstain.jpg
• Slide 12 http//www.ct.gov/dps/cwp/view.asp?a215
  5Q315022PM1
• Slide 13 http//static.howstuffworks.com/gif/lumi
  nol-crimescene.jpg
• Slide 14 http//wwwimage.cbsnews.com/images/2007/
  12/18/image3627828g.jpg
• Slide 15 http//diverge.hunter.cuny.edu/weigang/
  Images/18-03_precipitin_1.jpg
• Slide 16 http//www.eko.de/eko_web/img_files/mib
  i_top3.jpg
• Slide 17 http//library.thinkquest.org/04oct/0020
  6/images/bloodanalysis.JPG
• Slide 18 http//www.wagnerandson.com/images/drop1
  14.jpg

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References

• Slide 19
• http//upload.wikimedia.org/wikipedia/en/thumb/0/0
  d/BPA_ellipse_example.jpg/350px-
• BPA_ellipse_example.jpg
• Slide 20 http//content.answers.com/main/content/
  wp/en/a/a7/BPA_AOI.jpg
• Slide 21 http//bodmas.org/blog/images/secondary_
  wavelet_spatter.jpg
• Slide 22 http//www.spaceflight.esa.int/users/ima
  ges/gbf/ep-trom-samp.jpg
• Slide 23
• http//www1.istockphoto.com/file_thumbview_approve
  /4166625/2/istockphoto_4166625
• _close_up_crime_scene.jpg
• Slide 24 http//www.justice.gov.gu/images/gavel.j
  pg