Forensic Serology
Blood and other body fluids
Golden Rule
• If it’s wet and sticky and it’s not
yours…..DON’T TOUCH IT!
• Live long enough to get more out of your
retirement fund than you put in
Transfer of biological evidence
• Direct
• Indirect
– The biological evidence is
transferred to an item or at
the crime scene
– There is no direct contact
between the source and
the target surface
– The victim’s blood (DNA)
on the suspect’s clothing
– Semen on the victim’s
clothing gets onto a
hospital sheet
– The suspect was never in
contact with the sheet but
his DNA is there
Transfer of DNA
• Grab a glove
• What part of the glove are you touching?
• Did you transfer any skin cells?
Collecting a bloodstain
• It MUST be
•
•
photographed
To give orientation in
the scene
The photos will
provide:
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–
–
–
Location
Pattern
Condition (drying, wet)
Indication of volume
Forensic Characterization of
Blood
Is it blood?
– Presumptive testing at the scene
What species?
– What else will our test react with?
Can it be associated with a particular
person?
Is it a degraded sample or a mixture
Selecting a Presumptive Test
• Specificity – false positives
• Sensitivity – at what point does it not
work
• Easy to use
• Safe to use
• Non-destructive to scene or evidence
• Legal acceptability
• Chemical stability
Presumptive blood testing
• Indicates that blood MAY be present
• It does not tell what species the blood is
from
• All presumptive tests have false positives
What tests are available
• Phenolphthalein
• Luminol
• Hema-stix
• Pick the test(s) that work best for your
needs
We have chosen…
• Phenolphthalein
– 3 step test
– Easy to use
– Stable and sensitive
• Luminol
– Very sensitive
– Requires practice to interpret results
– Difficult to photograph
Phenolphthalein
• Used when you can
•
•
see the stain
The stain is swabbed
with either filter paper
or a sterile swab
The filter paper can
be folded into
quarters – to get into
small areas
Phenolphthalein
• The stain is rubbed
•
•
slightly (dry)
A portion of the stain
is transferred to the
paper or swab
The paper or swab
has the chemicals
applied to it – the
stain remains dry & is
not diluted
Phenolphthalein
• Alcohol/ Reduced (unstable)
•
•
•
phenolphthalein/ Hydrogen
Peroxide
1 drop of each in that order
A positive reaction is a pink
color within 3-5 seconds
The time of the reaction is
important
Phenolphthalein
• Sensitivity of 1: 5,000
• A false positive will
•
happen between the
second (reduced
phenolphthalein) and
third (hydrogen
peroxide) step
False positives occur
with vegetable
materials,
horseradish, oxidizing
agents
Hemastix
• Not designed for forensic purposes
• Designed to detect blood in urine
• Sensitivity of about 1:10,000*
• False positives
– Vegetables and oxidizing agents
• Do not dilute stain
• Touch dry strip to suspected stain
• Add one drop of distilled water
Luminol
• This is the LAST thing you
•
•
•
would do to look for blood
Used when you suspect
blood is present but you
can’t see it
Applied in complete
darkness
Results in the creation of
light
Luminol
• Once mixed it has a
•
•
shelf life of 8 hours
False positives include
some metals,
particularly copper,
oxidizing agents and
porcelain
A positive luminol
result should be
followed with
phenolphthalein
Luminol
• Luminol has a
•
sensitivity of 1: 1
million
Followed with
phenolphthalein
because of
differences in
sensitivity
Luminol photography
• Complete darkness
• Camera on tripod
• Bulb setting – 2
•
•
minute exposure
Bounce flashlight off
ceiling at end of
exposure
Close shutter
Collecting a wet stain
• If it can be taken –
•
•
•
take it
Soak the stain with
sterile gauze or a
sterile swab
If it is drying – let it
dry
Air dry the gauze or
swab out of direct
sunlight
Collecting a dried stain
• Take it if you can
• Scrape it using a sterile
•
•
•
scalpel
New scalpel for each
stain
Scrape into a druggist
fold & place in envelope
Scraping is preferred
because it does not dilute
the stain
Dried stain
• Swab it with a sterile
•
•
swab and distilled
water
DO NOT use saline –
it will break open the
cells
Air dry the swab prior
to packaging
Collecting Blood Evidence
• Take it
• Scrape it
• Swab it
Liquid Blood Samples
• Should be submitted at the same time so
the comparison can be done
• The tube used will depend upon what
testing you want done on the sample
Red capped tube
• No preservatives
• A sterile tube used for
general ABO grouping
• Not used much…
Gray capped tube
• Contains the
•
•
preservative sodium
fluoride
Prevents the
formation of residual
alcohol in blood
Used for BAC and
toxicology testing
Purple capped tube
• Contains the
•
•
preservative EDTA
An anti-coagulant that
keeps the cells from
breaking open
Used for DNA analysis
Finger stick kit
• An easier way to
•
•
collect a sample for
DNA analysis
Does not require a
phlebotomist
Make sure the person
is not a hemophiliac
Finger stick kit
• A small lancet is used
•
to stick the finger and
the blood drops are
placed onto four
quarter sized circles
Best to stick them on
the side of the finger
– the pad of the
finger tends to be
more calloused &
harder to get blood
from
• A fingerprint is then
•
•
taken to verify
identity
To prevent another
person from giving a
DNA sample
Good tool because
the sample can be
taken immediately
Known blood samples
• Liquid blood must be
• Tape over the stopper
• The expiration date
• The additive is the
refrigerated
on the tube is
important – it
guarantees the
sterility of the tube or
the chemistry
if it to be shipped
important part – the
color of the cap may
vary
Sex Crime Investigation
• Physical evidence
possibilities
–
–
–
–
Scene
Victim
Suspect
Items
Scene
• Exactly where did the
incident occur
– Sheets
– Comforter
– Condom used?
• Other items to place
victim there?
– Clothing
– Jewelry
– Cans/bottles
Suspect
• Collect the same
•
•
•
evidence that is
collected from the
victim
Penile swabs
Finger swabs
Suspect kits available
through the State Lab
Victim
• Kit – might be two
•
•
•
parts – urine sample
Paperwork from kit
Photos of injuries
Missing clothing or
other items (jewelry,
buttons)
It’s been _____ since it
happened…should I do a kit?
• Normally sperm can last 3-4 days in the
vaginal cavity of a living person
• Normally about 12 hours in the rectal
cavity of a living person
• Normally about 6 hours in the oral cavity
of a living person
State Lab Policy
• Females
– Kits collected more than 7 days post-assault
will not be accepted
• Males
– Kits collected more than 3 days post-assault
will not be accepted
• Exceptions
– Patient held captive and/or not able to be up
walking, bathing or showering
– Patient found unconscious
– Bedridden or wheelchair bound
From the literature…..
• Found in a frozen body’s vaginal cavity
after 19 days
• Found in a frozen body’s rectal cavity after
3 years
• Found in mummified body’s vaginal cavity
after 3 years
If in doubt…
• Have the kit done if the time frame is
close
• You also get the victim’s known samples
with the kit
• If you don’t get a result it is not a surprise
• Sexual Assault Forensic Examiners (SAFE)
• Medical personnel who have received
extensive training in evidence
documentation, preservation and
collection
Sex Crimes Kit Contents
• Oral swabs and smears
• Nasal swabs
• Nasal mucous sample
• Fingernails scrapings
• Known blood collection
• Known head hair sample
– 25 hairs total from the front, back, crown and
2 temporal areas
Sex Crimes Kit Contents
• Foreign material collection
• Debris collection
• Dried secretions
• Pubic combing
• Known pubic hair sample
• Genital/penile swabs
Sex Crimes Kit Contents
• Rectal swabs/smears
• Vaginal swabs/smears
• Cervical swabs/smears
• Miscellaneous swabs/smears
• Urine specimen
• BAC specimen
Reasons for not finding sperm
•
•
•
•
•
Acidic environment
Low sperm count
Time (since incident)
Poor quality sperm
Victim bathed
• Suspect didn’t
•
•
•
ejaculate
Bacteria
Condom used
It didn’t happen
Locating a semen stain
• Ultraviolet light is an easy
way to search
• Semen reflects light and
will fluoresce
• Stains can be located on
light and dark surfaces
• Useful for searching large
items
Locating stain using UV light
Presumptive Testing
• Acid phosphatase
• Indicates semen MAY be
•
•
•
present
Dark pink or purple
reaction within 20
seconds (time impt.)
No color change = no
semen present
False positives: vegetable
juices, vaginal secretions
& contraceptive creams
Confirmatory testing
• The presence of semen must be confirmed
after a positive presumptive test
• Semen is confirmed with:
– Sperm observed with a microscope
– Testing for the presence of the p30 antigen
DNA
• Deoxyribonucleic Acid
• First discovered in
1868
• 1953 – Watson &
Crick show the
structure of the
molecule
What does it mean?
Use of DNA in criminal cases
• The Blooding -
•
•
details a criminal case
in Narborough
England
One murder occurs in
1983 and a second in
1986
DNA proves it is the
same man but NOT
the man in custody
Use of DNA in criminal cases
• The police collect samples from all males
•
•
•
•
between ages 13 & 34
No suspect is identified
Colin Pitchfork has a friend provide a sample
under Pitchfork’s name
The friend is overheard telling what he’d done…
Colin Pitchfork is the first criminal apprehended
using DNA evidence
First use of DNA in U.S.
• The first criminal conviction occurred in
Florida in 1987
• Randall Scott Jones is convicted of murder
after his semen is identified in a homicide
victim
Different techniques
• 1986 – Kary Mullis
•
develops the PCR
technique
This enabled more
sensitive testing with
a much smaller
sample
Where is DNA found?
Everywhere!!!
DNA has been isolated in:
• Blood & bloodstains
• Semen & seminal stains
• Tissue & cells (particularly skin cells)
• Bones & organs
• Hair with root (nuclear DNA)
• Hair without root (mitochondrial DNA)
• Saliva (skin cells)
“Touch” DNA
• Sensitivity of DNA
•
testing allows for
results to be had from
items that were only
touched
Makes contamination
by us that much more
important
Evidence that is not suitable for
DNA Analysis
• Tears
• Perspiration
• Serum
• On their own these items are not likely to
yield DNA
• In reality skin cells are present in sufficient
quantity to get DNA from these items
Investigative sources of DNA
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Jewelry
Gun grips
Collars/cuffs
Hats
Chapstick/ lipstick
Popsicle stick
Gear shift lever
Steering wheel
Tattoo goo
Door handles
•
•
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Seal of Ziploc bag
Pipes
Chewed tobacco
Knife handle
Jeans – front pocket
seam
Airbags
Trigger
Latex and knit gloves
Baseball bat (both ends)
Eyeglasses
Rim of bottle/can
Contamination is a MAJOR issue
• Because of the sensitivity of the current testing
methods careful handling is critical
• Mishandling at the scene and in the lab can
create contamination
• Individually packaged gloves are becoming the
norm – to prevent transfer from reaching in to
the box
Non-biological contamination
• Soaps or chemicals interfere with the
procedure to extract the DNA
• This results in an inconclusive test or no
DNA being extracted
Non-human biological
contamination
• Bacteria and fungi present at the scene
degrade the DNA present
• The DNA gets degraded and results are
more difficult to interpret
• It does not get converted into somebody
else’s DNA
Human contamination
• By far the most important form of
contamination
• The mistaken addition of another humans
DNA during or after the sample collection
• Mixed sample – contains DNA from more
than one person and occurs before or
during the crime
• Transfusions do not interfere
Swabbing for DNA evidence
•
•
•
•
•
Sterile swab
Distilled water
Swab box
Wet the swab without
the water container
touching the swab
Roll the swab over
the area or through
the stain
DNA in the crime lab
• It will degrade if exposed to heat,
moisture, chemicals, UV light or bacteria
• Get the sample to the lab ASAP
• Freeze it - if it not being submitted
immediately – particularly if it is an epi-cell
swab (skin cells or “touch” DNA)
• Several techniques are possible –
depending upon the laboratory
Mitochondrial DNA
• Found outside the nucleus of the cell
• Usually outlasts nuclear DNA
• Maternally inherited – people with the
same mother have the same mito DNA
Mitochondrial DNA
Trust your siblings
Samples for mito DNA
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•
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•
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Hairs without root
Teeth
Skeletal remains
Finger/toe nails
Skin tissue
• Testing requires unique equipment and not
•
many labs do this testing
Regional labs are being established (CT. & NJ) –
check with State Lab for submission of samples
Familial Searching
• Searching a crime scene DNA sample
against the database to indicate who, in
the database, may be related to the DNA
recovered at the crime scene
• The scene sample has been searched and
there is no match in the database
Familial Searching
• Currently allowed in eight states
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California
Colorado
Wisconsin
Virginia
Michigan
Texas
Wyoming
Utah
Florida
Roaming Rapist
• Dereck Sanders
• Rapes occur from April ‘98 through March
‘03
• Convicted of 28 felony counts
• Brother is in DNA database
• Tracked Sanders to a McDonald’s and
collect his discarded trash
Grim Sleeper
• Lonnie Franklin Jr.
• 10 female victims from 1985-2007 in LA
• Possibly as many as 25 more victims
• His son was in the DNA database
• Police pose as busboy and collect his
items at a restaurant
National Missing Person Database
Program
• An off-shoot of CODIS
• Uses nuclear and mitochondrial DNA
• Two indexes:
– Relatives of Missing Persons
– Unidentified Human Remains
• The two are compared to associate
recovered remains with missing persons
Missing Persons
• Get a DNA sample
•
from mother, father
or siblings
If not available – DNA
samples from items
used by missing
person
– Hair brush
– Tooth brush
– Specimens from
medical work
Databases
• Combined DNA Index System (CODIS)
• A nationwide database of DNA samples
• Regional databases also exist and are then
uploaded into CODIS
• CODIS has over 1.6 million samples and
receives between 10k & 40k new samples
per month
Two indexes in CODIS
• Forensic Index
– Contains DNA profiles from crime scene
evidence
– Used to link crime scenes together
– ID’s serial offenders
– Helps to coordinate investigations – connect
the crime and other investigative info can be
compared
CODIS Indexes
• Offender Index
– Contains DNA profiles of convicted sex
offenders and other violent crimes
– All states now have legislation requiring a
DNA sample be submitted upon conviction
– Currently a backlog of about 500,000 samples
that need to be entered into the system
– This was an issue with the Dawn Rossignol
case at Colby
CODIS
• Contains about 80k samples from unsolved
•
•
•
crimes
These are searched against new samples being
submitted
8k samples have been matched from unsolved
crimes to convicts
3k have been matched to other samples from
unsolved crimes. Linking the crimes but w/out
ID’ing the perpetrator.
CODIS
• An initial “hit” in CODIS does not result in
immediate arrest
• It gives probable cause to obtain a new
sample and conduct a new test
• This provides a safeguard against clerical
errors or sample switching
CODIS
• Privacy concerns exist about the database
• Michael Chase case
• “John Doe” warrants
• Josh Deprez case
Maine Law
• Title 25 Section 1574
• Allows a DNA sample to be taken upon
conviction
• Sample collection allowed since 1996
• Based upon the initial offense charged –
taking into account plea bargains
Bitemark Evidence
• If there is an
•
allegation but no
visible mark – swab
the area
If there is a visible
mark swab it and
photograph it with an
ABFO scale
Bitemark Evidence
• The injury should be photographed at
regular intervals over the next week
• As the wound heals more detail may
become visible