Forensic Bio

Epithelial Cells

epithelium is a tissue composed of a layer of cells -lines the outside of the body and interior cavities and vessels in the body - outermost layer of skin is composed of dead stratified squamous epithelial cells, as are the mucous membranes lining the inside of mouths and body cavities

Squamous cells

are flat cells with an irregular flattened shape


more than one layer of cells


epithelium occurs mainly in the skin, it is also found in the mouth and nose providing a tough, impermiable barrier


a tough insoluble protein that essentially waterproofs the skin


doesnt contain a nucleus

Where can one obtain touch DNA from?

gun grip, baseball bat, knife handle, steering wheel, doorknob, phone, pen, documents

what kinds of things could contain wearer DNA?

hat, shirt, pants, shoes, underwear, glasses, gloves, jewelry

What is touch DNA?

-nucleated epithelial cells are transferred via touch to inanimate objects (cells move from the basal layer to the surface they become keratinized)-more successful when there is hard contact between the skin and the suspected surface or when the surface being touched has texture-difficult to obtain a suspect's DNA profile when directly swabbing the victim's skin-DNA profile usually obtained by performing low copy DNA analysis

Wearer DNA?

-Nucleated epithelial cells are transfered to areas of clothing that have the most contact with skin (collars, cuffs, waistbands of undergarments)-some labs cut or swab suspected stains and send directly to DNA for analysis; others extract the biological material and microscopically a portion of the pellet for presence of nucleated e cells


-not routinely identified-visible stains "sniff test"-the location of the stain and presence of cellular material implies sweat

ID of menstrual blood

-no definitive test-epithelial cells usually present-glycogen-doesn't clot-lactate dehydrogenase (LDH)-endrometrial cells from uterous may be identified microscopically

ID of breast milk

-contains low levels of salivary apha amylase (higher than other body fluids besides saliva)-exhibits flourescence at 450nm with orange filter-no definitive test (look at context of case)

Identifaction of Vomitus (ew)

-contents of one's stomach that have been forcibly ejected-no definitive test -look for various factors/circumstances of the case-presence of certain things can aid in ID -low pH (stomach acid) -distinctive odor (butyric acid) -partially digested food -amylase (vomit=increased saliva production) -pepsin (digestive enzyme)

ID of Bone

bones and teeth are best identified by an expert in osteology, anthropology, odontology etc.

What can the ID of Bone tell us?

-Area of the body the bone originated from (long short and flat bones)-aide in identifying the type of injury (shooting, stabbing, beating)- age, gender, ancestry-DNA source -Species

What does bone consist of?

Three layers: -periosteum= outside of the bone contains blood, lymph and nerve cells -the hard compact bone made up of crystalline mineral salts, calcium, collagen, and various growth factors -spongy bone tissue comprised of blood vessels and marrow

Identifying bone from non-bone

-Microscopic analysis-bone has a fairly compact surface w/some graininess-SEM and energy dispersive xray spectroscopy -elemental analysis of specimen -calcium to phosphorous ratio -useful when sample is extremely small, fragmented or damaged

Animal Bone vs Human Bone

-macroscopic examination-microscopic ecamination-species testing can be performed if there is tissue attached to the bone

Barr bodies

id of bar bodies (sex chromatin bodies) was used before forensic DNA profiling-interactive x chromosome-characteristic in nuclei of certain cells of mammalian females -smooth muscle cells, hair root sheaths, epidermal cells, and white blood cells (id of barr bodies should be performed by experienced examiners, must examine atleast 100 cells)


individual specific auto antibodies which perform a housekeeping function by ridding the body of dead and diseased cells-found in all mammals, in blood, saliva, urine perspiration, tears and semen


-product developed for antibody profiling, AbP-ID reads the ISAs found in all mammals

Antibody profiling

Everyone has a unique antibody profile - at birth, identical antibody of your mother -those profiles gradually change until about the age of 2, a stable one of a kind pattern is formed -from that point on the antibody profile never changes -identical twins have their own unique individual antibody profile


-a proprietary digital imaging software program that digitally quantifies the differences and similarities between any two developed AbP-ID test substrates-similarities between arrays expressed as a percentage (results in 2-5 hours)

What are the advantages of antibody profilint?

-a screening test for DNA submission-Bloodstain pattern analysis tool-remains identification-expanded criminal prosecution

Microbial-Vac System

The m-vac is a hand-held, non destructive, wet vacuum surface sampling device-manufactured by MSI-originally developed for pathogen testing-currently undergoing forensic validation

Advantages of Microbial-Vac System

The m-vac provides DNA extraction rates at a much higher rate of recovery than other methods (Swabs) -sample larger areas -extract more sample from any given area and surface -rapidly concentrate sample

General info of ID of other miscellaneous bio material

-RNA and DNA based assays are gaining prevalence in the literature-remaining bio fluids/materials are most often identified visually.microscopically and in conjunction with the contect of the case, or maybe not at all