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Forensic Biological Evidence > M3 > Flashcards

M3 Flashcards

1
Q

Sexual Assault Nurse Examiners (SANE)

A

A specially trained individual that performs the medical examination of complaints in sexual assault cases

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2
Q

Sexual Assault Response Team (SART)

A

Forensic nurses take a lead role in the coordinated response by the

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3
Q

sexual assault evidence collection kit (“rape kit”)

A

Complainants are take to a medical facility or a SANE/SART facility to attend to their medical needs and to collect relevant evidence using a

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4
Q

The Forensic Scientist’s Role

A

*Sexual assualt evidence collection kits are forwarded to the forensic lab for examination
*The forensic scientist’s primary role is the analysis of the physical evidence.
*If semen is present it helps to establish the corpus delicti
*If semen or other fluids are found, DNA typing is conducted to determine if there is a match to suspect or an exclusion.

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5
Q

3 types of sexual assault cases

A

1 Unknown offender (identification cases),
2 Known offender (consent cases), and
3 Sexual assaults involving children

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6
Q

Other forms of evidence that are important to consider

A

drug-facilitated sexual assault (DFSA)
Impression analysis of latent prints
Digital or other multimedia analysis
Chemical analysis of swabs
Fabric separation analysis of clothing
Firearms analysis of clothing for muzzle-to-target distance determination

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7
Q

Drug Facilitated Sexual Assault

A

*“date rape” drugs: rohypnol, GHB, ketamine
*All are depressants with amnestic effects, and are often used along with alcohol.
*These types of cases require toxicological analysis of the evidence.

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8
Q

Recommended to collect the following samples:

A
  • Peri-oral area, lips, and oral cavity
  • Posterior fornix and cervix (in the post pubertal female)
  • Peri-anal folds, anus, and rectum
  • External anogenital structures (male or female)
  • Neck
  • Breasts
  • Palm of hands
  • Fingernails
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9
Q

Sample Collection

A

Oral sample, external genital sample, vaginal/cervical sample, penile sample, perineal sample, anal/rectal sample

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10
Q

Wet-mount evaluation

A

*Some jurisdictions require examiners to conduct wet-mount examinations of vaginal/cervix secretions for motile and nonmotile sperm in cases in which a male suspect may have ejaculated in a patient’s vagina
*Because sperm motility decreases quickly with time and removal from the vagina/cervix, wet-mount evaluation during the exam can provide the only opportunity to see sperm motility.
*The presence of motile sperm may help narrow the timeframe that the crime could have occurred.

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11
Q

Slides and Smears:

A

*Creating slides and smears at the medical exam site from oral and anogenital samples is UNNECESSARY and should be elminated, since the slides prepared during the medical exam generally have more epithelial cells, bacteria, and other debris.

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12
Q

Suspect Sample Collection

A

*Expect for the routine reference sample collection (usually in the form of a buccal swab), a full medical-forensic examination or other suspect sample collection should ideally be completed by a medical-forensic examiner or appropriately trained individual.
*collected from a suspect by law enforcement personnel in accordance with a lawful court order.

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13
Q

Semen Function

A

*Lubricates sperm duct/urethra
*Nutritive and protective liquid medium for sperm to travel in.
*Alkaline environment which protects the sperm against the acidic nature of the vaginal tract.

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14
Q

Semen components originate form several sources

A

Seminal vesicle fluid
Prostatic fluid secretions
Epididymis and bulbourethral glands

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15
Q

What could affect how many Spermatozoa per ejaculation?

A
  • Medical conditions
  • Genetic background
  • Diet
  • Smoking
  • Illicit drug use
  • radiation
  • environmental toxins
  • undescended testis
  • varicocele
  • trauma
  • Aging
  • Skinny jeans (?!)
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16
Q

Oligospermia

A

abnormally low sperm count

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17
Q

Aspermia

A

no sperm

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18
Q

Pre-ejaculation fluid

A

*Originates from bulburethral gland (also known as cowpers gland).
*Functions as a natural lubricant during intercourse
*If there is absence of full male ejaculation, this fluid could have forensic significance.
*Widely accepted it contains traces of acid phophatase and prostate specific antigen; no evidence to date of the presence of semenogeliln.

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19
Q

Parts of Sperm Cells/Spermatazoa

A

1 Head
2 Middle Piece/neck
3 Tail

20
Q

Why is semen important in an investigation?

A
  • Evidence in sexual assault cases
  • Can help prove a crime was committed
  • Can identify the perpetrator
21
Q

Semen Visual Search

A

i White light
ii Alternate Light Source (ALS)
iii UVA Light (Woods Lamp Technique)

22
Q

Semen Acid Phophatase (AP)

A

Acid phosphatases are a class of enzymes found in various living tissues
*Mammalian liver to cauliflower stem juice
*Diseases of the bone, such as Paget’s disease or hyperparathyroidism, diseases of blood cells, such as sickle-cell disease or multiple myeloma or lysosomal storage diseases, such as Gaucher’s disease, will show moderately increased levels
*Breast milk, urine, and vaginal secretions

i Spot Test
Purple

23
Q

PAP

A

Semen contains very high levels of prostatic acid phosphatase (PAP)
*PAP is an enzyme secreted by the epithelia cells of the prostate gland
*High levels of PAP in blood may indicate prostate cancer
*Its level proportionally increases with prostate cancer progression
*AP levels in semen not affected by vasectomies
Spot and Mapping test

24
Q

Acid Phophatase Test (AP) Spot Test

A
  • Brentamine Fast Blue B Test
  • Will react with semen diluted 500-fold
  • Another rapid color change test
  • by far the most commonly used
  • First introduced in 1957 by Stuart Kind
    Positive reaction is purple
25
Q

Confirmatory Tests for Semen

A

a) Microscopic identification of sperm cells with Christmas Tree Stain, or Hemotoxylin & Eosin
b) Sperm HyLiter
c) Detection of Prostate-Specific Antigen (ABAcard P30, also Seratec PSA Semiquant)
d) Semenogelin - human semen specific protein (RSID)

26
Q

Christmas Tree Stain Confirmatory Test

A
  • Microscopic examination for sperm cells
    ~ Spermatoazoa - plural
    ~ Spermatoazoa - singular
  • Histopathological staining helps distinguish sperm cells from epithelial cells
  • Two Dyes used:
    ~ Nuclear fast red - Stains heads read
    ~ Picric acid - indigocarmine green (PIC) -Stains tails and neck green
27
Q

Sperm Hy-Liter Confirmatory Test for Semen

A
  • Reported to be specific to spermatozoa heads
  • Contains human sperm specific antibody that causes sperm head to fluoresce
  • Contains another fluorescent dye which allows for the viewing of all cell nuclei
28
Q

Prostate-Specific Antigen (PSA or p30) Confrimatrory Test for Semen

A
  • PSA is a glycoprotein produced by the prostate gland with a molecular weight of about 30,000 kDaltons
  • Liquefies semen and is instrumental in dissolving the cervical mucous cap for sperm entry
  • Can confirm in AP+ samples that do not contain sperm
  • Test relies on antigen (PSA) and antibody interaction
29
Q

Seminal Vesicle-Specific Antigen (RSID) Confirmatory Test for Semen

A
  • Major vesicle-secreted protein in semen
  • Two types:
    ~ Semenogelin I (Sgl)
    ~ Semenogelin II (SgII)
  • Protein responsible for coagulation after ejaculation
  • Higher concentration in seminal fluid than PSA > greater sensitivity of detection
  • Not found in urine, milk, sweat > more specific assay
30
Q

Is Saliva common in Forensic Investigations?

A
  • Forced Felatio
  • Forced Cunnilingus
  • Forced Anilingus
  • Spitting
  • Coughing/Sneezing
  • Bitemarks
    Transfer to objects (bottles, cigarettes, envelopes, stamps, sex toys, gags, airbags etc.)
31
Q

Saliva

A

Mostly water with small amounts of electrolytes, proteins, antibodies, and enzymes.
Physiological role - breaks down carbs/startch in mouth

32
Q

Amylase

A

enzyme that breaks down complex carbohydrates into smaller sugar molecules

33
Q

Beta-Amylases

A

~ Plant and bacteria
~ Cleave only terminal reducing end of polysaccharide chain
~ Mainly involved in the fruit ripening and seed germination

34
Q

Alpha-Amylases - 2 isoenymes

A

~ Human, cleaves starch at its internal bonds, at random a1 ->4 linkages, allowing for compound hydrolysis - total breakdown of starch to maltose/glucose/dextrin

35
Q

2 Major isoenzymes:

A

Salivary a-amylase (HAS) & pancreatic a-amylase (HPA)
~ Indistinguishable at the enzymatic activity level
~ Salivary amylase is a hydrolytic enzyme
~ Salivary amylase also referred to as ptyalin

36
Q

Saliva Presumptive Test

A

Look for the presence of a-amylases
~ Measurement of enzymatic activity of total amylases
~ Cannot distinguish HAS from SPA and non-human amylases

37
Q

Saliva Confirmatory Tests

A

Look for the presence of a-amylases
~ Measures the presence of HAS
~ Direct detection of HSA

38
Q

Examples of Saliva Test
Presumptive

A
  • Visual/UV light
  • Histological
  • Starch iodine
  • Phadebas
  • Saligae
  • RSID
39
Q

Saliva Presumptive Test Visual Examination

A

~ Similar to techniques for semen visualization using ALS
~ Visualization of Fluorescence with 470 nm excitation wavelength + orange goggles
# Saliva stains do not fluoresce as intensely as seminal stains
~ Microscopic examination with histological staining to identify buccal epithelial cells

40
Q

Urine Presumptive Test - DMAC

A

Para-dimethylaminocinnamaldehyde (DMAC) assay
* Simple and rapid
* Most common presumptive test
* DMAC reacts specifically with urea
* Does not react with creatinine, ammonia, or uric acid
* Urea present in other body fluids, therefore presumptive
* Produced by all mammals, amphibians, and some fish

41
Q

Urine Presumptive Tests - Jaffe

A

The Jaffe test is used to determine the presence of creatinine in urine
The formation of this orange color indicates the presence of urine

42
Q

Urine Presumptive Tests - Uritrace

A

Creatinine is produced during normal muscle metabolism
* Produced by Abacus Diagnostics
* Uses colorimetric mechanism of action

43
Q

Urine Presumptive Tests - Urease Assays

A
  • Ammonia is detected using bromthymol blue, an acid-base indicator -> blue color
  • Ammonia can also be detected with manganese and silver nitrates -> black color
  • Ammonia can also be detected with manganese and silver nitrates -> black color
44
Q

Urine Confirmative

A

Identification of Tamm-Horsfall protein (THP) (Uromodulin)
*Identification of 17-ketosteriods
*androsterone glucuronide, androsterone sulfate, DHEA sulfate, etiocholanolone glucuronide, and etiocholanolone sulfate

45
Q

Presumptive Feces Test

A
  • Dection of urobilinoids, including stercoblilin and urobilin
  • Formed during the degradation of heme; final products of red blood cell breakdown
    Schlesinger Test
    Edelman Test
    *Cannot distinguish between human and other mammalian feces
    *Low cell count and high bacteria content make testing difficult, but not possible
46
Q

Menstrual Blood Presumptive Test Examples

A
  • D-dimer=fibrin degradation product, a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis.
  • Assays for D-dimer detection:
    ~ ELISA
    ~ Latex agglutination
    ~ Immunochromatic assay
  • Origin in clinical field - diagnosis of thrombosis
    ~ Clearview Simplify D-dimer devices
47
Q

Menstrual Blood Confirmatory Test Examples

A

Lactate dehydrogenase (LDH) is an enzyme that plays an important role in glycolysis
* The five isoenzymes of LDH (LDH1-5) can be separated by electrophoresis
* Circulatory Blood;
~ LDH 1,2,3 - predominant
~ LDH 4,5 - minor
* Menstrual Blood;
~ LDH 1,2,3 - minor

Forensic Biological Evidence (3 decks)

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