4341 - Exam #2

history of electrostatic lifting

- May 1965: 3 Metropolitan Police in Japan used woolen cloth to produce static charge and celluloid sheets as a lifting material - July 1970: Kato Masao developed a static electricity machine with 14,000 volts and had an electrode plate and a black vinyl sheet; first electrostatic lifting device - 1983: Foster and Freeman produced first portable ESLD with rechargeable batteries and separate pieces of film

gelatin lifters

- can be used when ESLD fails - black, white, and transparent in a variety of sizes - gelatin layer is low tack with minimal stickiness - used on materials that cannot be removed from the scene - used with fingerprint powders have developed impressions

leuco crystal violet

- colorless form; very popular at crime scenes - excellent results for visualizing bloody impressions at a crime scene

diaminobenzidine (DAB)

- colorless that reacts with hemoglobin derivatives to produce a dark brown insoluble residue in the presence of hydrogen peroxide - must be freshly prepared prior to use

factors affecting the quality and detail of footwear patterns on bodies

- depth and detail of shoe design - degree and speed of impact - angle of shoe - clothing interference - victims movement at the time of impact

using gelatin lifters

- do NOT use a fingerprint roller; is can result in a 5 mm difference in length - must remain in place at least 5 minutes before removing

bluestar

- does not alter the DNA in suspect blood stains - total darkness is not required

applications of ESLD

- dry impressions can be lifted from any surface - will not work on wet impressions - if failed, the impressions is not destroyed and another method can be used - impossible on dirty surfaces as too much dirt may be lifted - if shoe is sticky or damp and walks through a dirty surface, a negative impression may be lifted

two categories of injuries

- dynamic loaded: high impact of shoe with victim - static loaded: standing on a victim

supplies for lifting 2D impressions

- electrostatic lifting devices - footprint size gelatin and adhesive lifting material - silicone casting materials

cleaning dust from impressions and lifts

- excess dust can be carefully cleaned from impressions and lift - CANNOT BE DONE WITH NEGATIVE DUST LIFTS

potassium thiocyanate

- first reported in 1963 in Japan - reacts with the iron in soil

lifting with dental stone

- for indented impressions: indentation materializer (IM) and electrostatic detection apparatus (ESDA)

specialized lighting and forensic photographic methods

- high contrast photos and the use of filters - oblique light - cross polarization - UV - infrared - ALS

two additional physical methods

- iodine fuming: reacts with grease or fat content of the prints; useful for wet impressions, not dry - cyanoacrylate ester fuming (superglue): fingerprinting; can be used for footwear; excellent results with wet origin impressions on most nonporous substrates; using on bloody impressions with prevent any further enhancement potentials

bromophenol blue

- lift muddy or dusty impressions and use bromophenol blue in the lab - reacts with calcium carbonate causing impression to turn blue with humidity, in drier climates it will turn yellow

acid yellow 7 (AY7)

- nonporous substrates - not recommended on absorbent substrates

handling and storage of the ESLD lifts

- paper stock file folder or a photographic box; taped in place - do NOT reuse folders

must have a good ground

- poor grounding may occur with uneven or textured surfaces - air pockets can be smoothed out with a fingerprint roller - allow lifting film to stay in place for at least 2 seconds (charge on film is discharged, reduces static shock when film is lifted)

lifting impressions with Mikrosil

- silicone based - good for lifting powdered impressions

amido black (AB)

- stains blood proteins dark blue/black - nonporous materials - 2g AB in 100mL glacial acetic acid and 900mL methanol for staining - 900mL methanol and 100mL glacial acetic acid for rinsing

ninhydrin

- triketohydrindene hydrate - not an enhancement process utilized at crime scene - reacts with amino acids in perspiration

adhesive lifters

- used the most in the US than any other method - poor results and poor contrast - not recommended for lifting original or powdered impressions - can be used in emergency situations

factors affecting choice of enhancement technique

1. composition and consequent limitations of the surface material 2. texture and porosity of surface 3. condition of the surface 4. composition of the impression 5. color of the surface 6. wet or dry origin 7. humidity 8. location of application 9. logistics involved in and the availability of the technique

modern ESLD

- 10,000-15,000 volts; very low amp - ground plate - metal hand-held probe - special lifting film - rubber roller

shoe sizing systems

- 1688, Randal Holme: based on 1/4 in system - 1880, Edwin B. Simpson: first detailed shoe sizing system; introduced half sizes - mondopoint - a concept intended to become an international standard; not commonly used

enhancement of bloody impressions

- 6 - 10 impressions can be left by the amount of blood typically held on a shoe or naked foot - socked feet can potentially hold more blood and produce more impressions

recovering blunt force pattern evidence

- ALS and chemical enhancement may be utilized for lifting the impressions - clothing can also be evaluated for patterns - shaving areas of the body may be required - patterns may be traced using clear acetate

2 discoveries that led to the mass production of footwear in the 19th century

- Charles Goodyear, 1839: vulcanization process of curing rubber which made it possible to produce footwear with rubber soles - Elias Howe, 1846: invented sewing machine

GL v ESLD

- GL best for wet impressions - use ESLD first for dry, then GL - when searching large areas, ESLD is more practical and successful - GL is superior on most substrates and also for wet impressions

scanning gelatin lifts

- GLScan utilizes a moveable vacuum bed to hold the gelatin flat and passes the gelatin beneath the line scan camera and a high intensity light

acid fuschin (acid violet 19) and hungarian red (intro in 1996)

stains blood protein components a deep magenta color

When lifting, a CSI or footwear examiner must transfer the impression from the original substrate to one of ______ contrast.

better

positive transfer

material deposited on a substrate

lifting

process of transferring a 2D impressions from its original surface to a surface that will provide a better contrast

pathfinder ESL unit

- Robert Milne; 1995 - 4 x 6 inches (small), but with small lifting power as larger versions - high voltage, low amp

history of shoe making

- Thomas Beard: America's first well-documented shoemaker - Lyman Blake, 1858: invented a sewing machine to attach the sole of the shoe to the upper - Jan Ernst Matzeliger, 1883: invented the first lasting machine

fixing blood with 5-Sulfosalicylic Acid before chemical enhancement

- aids in permanently adhering bloody residues to the substrate; without this step, bloody prints could readily be destroyed - precipitates the basic proteins which prevents leaching or diffusion of the blood

degradation of impressions using gelatin lifters

- amount of degradation is affected by: interaction between lifted material and gelatin, substrate, and whether a cover sheet was reapplied - do NOT reapply the cover sheet - gelatin lifts of powdered lifts have shown no loss of detail as long as they are not covered

factors affecting the severity, extent, and appearances of blunt force trauma injuries

- amount of force delivered - time over which the force is delivered - region struck - body surface - type of weapon - condition of body being struck

protein stains or dyes

- best used on nonporous substrates where background staining will not be a problematic

lifting 2D footwear impressions

- can be composed of any materials from blood to mud to oil to dust - can be very heavy or very light - can contrast very well with substrate or be very faint so as not to be seen

ESL film is made out of...

...polyester film (mylar).

methods of enhancing 2D impressions

1. ALS 2. physical methods (powder and lifting) 3. chemical reagents 4. digital enhancement techniques

blunt force trauma wounds

1. abrasions 2. contusions 3. lacerations 4. fractures of the skeletal system

what method of lifting should be used?

depends on the surface and context of the impression (wet or dry, material, thin, absorbent)

chemical methods of enhancement for non-blood impressions

potassium thiocyanate, physical developer, and bromophenol blue

negative transfer

shoe removes residue from surface