Forensic Serology Flashcards
may also be involved in DNA analysis and bloodstain pattern analysis.
Forensic Serologist
is the detection, classification and study of various bodily fluids such as blood, semen, fecal matter and perspiration, and their relationship to a crime scene.
Forensic Serology
is the study and examination of bodily fluids that is used in forensic science as a means of segregating fluids excreted by assailants or attackers in varying criminal acts. These acts can range from physical assault to sexual assault, right through to the act of murder and all of them will have an element of fluid secretion attached to them.
Serology
How Serology Helps in Crime
•Serology allows the forensic scientists to segregate these bodily fluids when found at the scene of the crime and then perform a variety of tests on them in order to identify where these fluids originated from - or most importantly - who they came from.
One important aspect of Serology is determining whether or not stains resembling blood found at a crime scene are actually blood or some other stain that bears a similar resemblance.
1
Serology is split into two categories of investigation:
Presumptive testing
Confirmatory tests
These tests provide two separate means of producing a result. One is to use compounds that can have an effect on blood when introduced to it. These results are a simple and quick way of proving that samples are actually blood especially if time is of the essence.
- Presumptive Testing:
This is a more involved set of tests that are carried out using samples of what is believed to be blood and mixing them with a chemical compound that reacts adversely with haemoglobin, the resultant factor being the production of crystals under the microscope that can be identified as blood.
- Confirmatory Tests:
- are carried out to prove that these stains are in actual fact blood; and, more importantly, human blood. This is particularly important if the deceased’s body has been found outside where it may be possible that animal blood has been spilled on the ground at some point.
It is important that these tests - either one of them
Presumptive testing
Conclusive tests
Other Important Uses of Serology
Serology, in addition to examining and identifying blood, is used to ________ semen, saliva, sweat and even human feces. This can be achieved in the instance of _____ as it is covered in a mucus membrane to enable expulsion from the body.
identify and categorize
feces
Other Important Uses of Serology
Serology also has a use in proving if _________ has taken place; this has become a necessary element of forensic science given the rise in sexual assaults and cases of rape. The processes used by a Serologist can help time intercourse and also help prove that unlawful intercourse actually took place.
unlawful sexual intercourse
It is important to note that although a large percentage of the population are classed as ‘____1___’ there are a smaller percentage of people who are ______2_____.
- secretors
2. non-secretors
exhibit elements of their blood’s protein when they secrete other bodily fluids
Secretors
will not have levels of protein from their blood in their bodily fluids.
non-secretors
Other Important Uses of Serology
Secretors and Non-Secretors
Testing the bodily fluids of secretors will reveal a result but ____1___ make it difficult for Serologists to gain any results so ____2____ from these individuals must be tested in order to provide any level of positive result.
- non-secretors
2. blood
Other Important Uses of Serology
Again it is important to note that these procedures are used when other means of identification yield no results and although these tests may prove accurate other means of identification should be used, leaving this kind of scientific evidence to provide additional weight to any ______
legal proceedings.
Body fluids test in serology
blood, semen, fecal matter and perspiration
- Examination of the shapes, locations, and distribution patterns of bloodstains
- To provide an interpretation of the physical events which gave rise to their origin.
Bloodstain Pattern Analysis
- Origin(s) of bloodstain
- Distance of bloodstain from target
- Direction from which blood impacted
- Speed with which blood left its source
- Position of victim & assailant
- Movement of victim & assailant
- Number of blows/shots
Blood stain pattern analysis
The _______ of bloodstain increases as the height increases
diameter
Blood Stain Pattern
Passive
Transfer
Projected
Reconstruction
PTPR
is a protein-rich body fluid originating primarily from the prostate and seminal vesicles.
Seminal fluid
commonly referred to as “sperm,” are the male gametes, or sex cells, produced in the testis.
Spermatozoa
Not all men produce spermatozoa.
True
Not all semen stains are visible to the naked eye
True
•It is applied to pre-screen evidence in an effort to identify discrete areas for Acid Phosphatase testing
Alternate light source (ALS)/UV light
Many body fluids fluoresce when excited with light at ____-nm wavelength.
450
________ have the tendency to fluoresce more intensely than most other body fluids.
Semen stains
Considered as a presumptive identification of seminal fluid because other body fluids might also give a positive reaction
Acid phosphatase Test
Identification of an enzyme known as ______
acid phosphatase.
Purple Color
Acid Phosphatase
Confirmatory Testing of Semen
Microscopic Identification of Spermatozoa
can be smeared onto a microscope slide and then stained for visualization.
Positive swabs or a small cutting from a positive stain
are sometimes referred to as the “Christmas Tree stain”.
Nuclear fast red
(red stain) and picroindigocarmine
(green stain)
NP
Watery substance located in the mouth
Secreted by salivary glands
Saliva
Saliva
•____% water
•____ % electrolytes, mucus, glycoproteins, enzymes, antibacterial and bacterial compounds
- 5%
0. 5%
A catalytic test for the detection of saliva is based on the enzymatic activity of alpha-amylase.
PHADEBAS AMYLASE TEST
At the end of this lecture the participant will able to:
- Define what is chain of custody
- Identify what packaging materials is needed and personal protection equipment
- Identify what part of packaging will provide identity of the evidence and maintains its integrity.
- List three forms of markings on an evidence
- List the documents required for biological evidence
Biological Evidence Collection Procedure
Record of individuals who have had physical possession of the evidence.
Chain of Custody
“The fewer people handling the evidence, the better, the lesser chance of contamination and a shorter chain of custody for court admissibility hearings”.
Integrity of chain of custody
Materials needed in Biological Evidence Collection Procedure
- Paper bags
- Permanent markers
- Evidence tape
PPE
Personal Protection Equipment
Gloves mask eye protector headgear body suit
G-MEHB
-maintains the integrity of the specimen; to further prove that no tampering took placed.
Seal
Integrity seal
May use commercially available ______ tapes.
tamper-proof evidence
May use scotch or masking tapes, ____,____,____for tamper proofing.
marked, initialed, or signed
MIS
Do not use staples.
True
Information to ensure that the items can be identified by the collector anytime in the future.
Markings
Markings
This precaution will help immeasurably to establish the _____ of the collector’s report or testimony and will effectively avoid any suggestions that the item has been _____.
credibility
misidentified
Markings of Evidence
What are indicated in the markings?
•Case number.
•Identifier (letters, numbers, or combination)
•Time and date of collection.
***It is also important to note the place or location where the evidence was collected.
CITP
Ideal manner of packaging
1) Integrity seal
2) Initial and signature of the collecting officer
3) Content
4) Turned over by
5) received by
IICTR
Improvised manner of packaging
ICDLxxx
- Identifier
- Soco case number
- Specimen description
- Location where the specimen was found
- Time or Date of collection
- Name and signature of collector
* seal (scotch tape) with signature or initials or any identifier for the collector
Information Required in a Letter Request:
- Brief summary of the case.
- Specimen description including source.
- Packaging.
- Markings
BsSdPM
Specimen Description, Packaging and Markings:
In this connection, may we request from your good office that a serological test be conducted on the following, to wit;
a. One (1) T-shirt with alleged bloodstain recovered from the suspect, placed in a brown paper envelope marked as “CCB-1”.
b. One (1) knife with alleged bloodstain recovered from the suspect, placed in a brown paper envelop
Concentrate on what cannot lie… The Evidence
Gil Grissom
