Criminal Inv-Chapter 4, Circumstantial Evidence Flashcards
Two kinds of proof
Direct evidence
circumstantial evidence
direct evidence
eyewitnesses who have, through one or more of their five senses, experienced something relative to the crime in question
circumstantial evidence
evidence from which an inference can be drawn and which includes items such as physical evidence. person fingerprints,
Major type of circumstantial evidence
weapons, blood, imprints or impressions, tool mark, haris, fibers, glass, paint and questioned documents
physical evidence can be divided into 2 broad categories
class individual
class evidence
cannot be linked to a particular person or an object but only to a class of objects. Includes: glass, paint, shoe prints, ballistics, fibers and tool marks
individual evidence
can be linked to a person or a specific object. Best examples is fingerprints. One individual evidence that would directly identify a person would include palm prints, sole prints, voice prints, bite mark and even ear and lip prints.
ballistics
identification of firearms, bullets. cartridges and shotgun shells
interior ballistics
refers to functioning of firearms thru the firing cycle
exterior ballistics
study of projectiles in flight.
firearms should be picked up by their rough or checkered wooden portions, if possible or any external metal portion except
trigger guard and trigger area.
gunshot residue examination (GSR)
applying adhesive tapes to person ‘s hands. Tapes then sent to crime lab where a scanning electron microscope interfaced with an energy-dispersive X-ray. The search is for presence of the major components in a center-fire cartridge:antimony sulfide, barium nitrate and lead styphnate, as well as supporting metallic particles of zinc, copper, nickel
exothermic reaction
compounds and elements are deposited on a persons hands when they fired a weapon and they undergo an intense exothermic reaction due to rapid increase in temperature followed by a sharp decrease. This supercooling phenomenon leads to a unique spheroidal formation that is generally not observed in the natural environment
relatively fresh bloodstains generally appear to be
reddish-brown in color; howeverover-time the stain can appear to be red to black, appear to be green, blue or even grayish white.
kastle-meyer color test
determination of whether or not the stain is blood is made by this test. Test is based on the reaction with the enzymes in the blood which causes the test strip to turn a deep pink color
blood test strips are available under the trade name
Hemastix, are useful presumptive field test for blood