Crime Scene Investigation Midterm

physical evidence

real, tangible and can be used in both criminal and civil trials. can provide either class or individual evidence

criminal trials

beyond reasonable doubt burden of proof (99%)

civil trials

preponderance of the evidence burden of proof (51%)

class evidence

cannot discount contributor but does not mean sole contributor like carpet fibers that are found across the building

individual evidence

applies to one person, and can prove they did it

first job of first responding police officer

acquiring medical assistance for injured victims: medical personnel avoid disturbing evidence and approach the victim by an indirect route

second job of first responding police officer

detaining any potential suspects or witnesses: statements taken from victims, witnesses, and suspects

third job of first responding police officer

securing the crime scene to the greatest extent possible: the boundary is sealed off, and guards are posted at the entry to the crime scene if needed

• all civilians and unauthorized personnel excluded

fourth job of first responding police officer

calling for any additional personnel needs such as other officers and/or forensic investigators: the personnel required depends upon the nature of the crime scene

officer safety issues at a crime scene

1. crimes in progress or suspects still on scene. Perform a protective sweep

2. natural hazards that may inhibit/harm the initial responder

3. man-made hazards that might endanger initial responders

primary rule of emergency care is

life saving always takes priority over evidence preservation

three factors or areas of consideration for a crime scene are

1. primary focal points

2. natural entry and exit points

3. secondary scenes

primary focal points

• body/large blood pools

• areas ransacked or disturbed

• areas where evidence such as shell casings or money are strewn about and are immediately obvious

inner scene

actual crime scene, where only authorized investigators and crime scene technicians operate

working area

this is an area surrounding the inner scene, where other support police may enter, equipment is staged and evidence is brought to

outer area

everything on the outside of the second barrier, where onlookers, media and others may gather

securing the crime scene

a detailed log is kept of personnel movements in and out of the crime scene. Includes personnel names and time of entry/exit

look but don’t touch

the walkthrough - initial survey of the crime scene, opportunity to determine the nature and extent of the crime

searching the crime scene

must be thorough and systematic. Pattern depends on the size and locale of the scene and number of collectors

circle search

excellent pattern in most interior or confined exterior scenes

• not effective in large exterior scenes or cluttered areas that impact on the movement

• searcher moves inward or outward from a starting point

strip search

excellent in exterior scenes where a large area must be examined

• visual alignment to the strip is good for most situations, but as the area to be searched grows, it becomes more difficult to maintain a visual reference of the lanes

• physically laying out the strips with string or tape can help maintain the order

line search

variation of the strip search where multiple searchers follow a single strip in one direction, while on-line with each other

• excellent for exterior scenes over rough terrain

• usually requires supervisor(s) to maintain direction and alignment of the involved searchers

Grid search

provides for multiple views of the same ground by the same searcher from different perspectives

• another variation on the strip search

• searchers follows strips in one direction, then cuts across the scene in another set of strips, oriented 90 degrees to the first

zone search

to break a larger scene up into functional areas, that are then searched using some other patterned technique (requires more than one person)

• used in several variations

• another variation is to deal with small confined spaces where no patterned search will work

catch-up

the crime scene investigator is constantly encountering new evidence and this requires stepping back in the process to play _______.

this is a constant behavior.c

chain of custody

A list of all persons who came into possession of an item of evidence

• must be established whenever evidence is presented in court as an exhibit

OJ Effect

facts of the case do not favor the defense, so they focus attack on individual items of evidence, proper handeling, and chain of custody

CSI effect

unrealistic expectations on behalf of jury, mostly as a result of entertainment shows

photographs

best source of documenting scene accuracy - document the condition and layout of the scene as found

unaltered condition

most important prerequisite for photographing a crime scene is for it to be in ____________

logical succession

when photographs show the overall scene first, then work down to individual pieces of evidence that jurors in the trial can easily relate back to the larger scene

four minimum photographs

1. overview photograph

2. medium range photograph

3. close-up photograph

4. close up photograph with a scale

in situ

as found, describes documenting crime scene

fragile evidence

evidence that should be photographed as soon as possible

Exterior overall photographs

need views toward the building and views from the building

interior overall photographs

the bridge between the exterior overall photographs and the individual items of evidence within the crime scene

midrange photographs

once an item of evidence has been selected to be documented, it’s _________ photograph is taken, followed by close-up photographs of the same item of evidence

also known as evidence establishing photographs

the close-up and the evidence establishing photograph go hand in hand

set-up for midrange photograph

position yourself an equal distance between a FIXED object (reference point), and your point of interest, in order to show realistic perspective i.e. isosceles triangles

close-up photographs

taken at 90 degrees angle to the object, with and without evidence markers and scales

three cardinal rules of good photography

fill the frame, maximize depth of field, keep the film plane parallel

fill the frame

zoom in or get closer

maximize depth of field

variable range from foreground to background of what appears to be in focus. If things are out of focus, it isn’t a fair and accurate representation of the scene

Exceptions to film plane parallel

windows or mirrors, highly reflective subject, and not enough room to get parallel

recurring problems with crime scene photography

1. identification issues

2. orientation issues

3. confusion issues

4. incomplete documentation issues

identification issues

photographs are taken of the items and the photo fails to illustrate what it is in the picture

orientation issues

involve creating photographs where the viewer is lost i the scene or has no orientation

• taken of an object with no scene reference (e.g. where is it in the scene)

confusion issues

creating photographs where the viewer is unclear of which item is being photographed or which photo came first

• show the scene in altered states

incomplete documentation issues

too few photographs are exposed - methodical scene processing techniques help eliminate this issue

oblique lighting

creates shadows, which makes it easier to see the 3D aspects of the patternb

bounce flash

aiming the electronic flash at a ceiling or side wall to soften the light reaching the primary subject, because the farther light travels to reach a subject, the softer (dimmer) it will be when it gets there

• optimal location on the ceiling to aim the flash, to minimize the total distance the light has to travel, is at a point that is midway between the photographer and the subject matter

body photography

1. overhead shot

2. full-face shot/profiles

3. close-ups of the bod

can also divide the body into two shots (head to waist and waist to feet)

when body is moved, photographs are repeated

midrange body photograph

necessary to take showing wound’s relationship to a fixed feature of the body

concerns relative to wounds/injuries of sensitive areas

permission, same-sex photographer, exclusion of unnecessary areas of skin

video photography

functional supplement to crime scene documentation, but does not replace any documentation product

• turn off audio unless intending to narrate

video photography critical mistakes

• planning too quickly

• not keeping the camera on an item long enough

• inappropriate comments made in the audio track

friction skin

skin that has raised ridges and indented furrows

rolled fingerprint

reproduction of the ridges of the finger created by rolling that finger in a thin medium of ink or on a livescan scanner plate

scientific basis of fingerprint

fingerprints are permanent and individually unique

general fingerprint patterns

loops, whorls, arches

loops

60-65% of the population

ulna - flowing toward little finger

radial - flowing toward the thumb

both loops and whorls have identifying characteristics known as the core and delta

must have one delta

whorls

30-35% of the population

minimum of 2 deltas 

series of almost concentric circles

arches

only about 5% of the population

plain: a smooth flow of friction ridges, entering from one side and exiting the other opposite side

tented: a spike in the central pattern area, sharp upthrust or spike, or the ridges meet at an angle that is less than 90 degrees

do not have type lines, deltas, or cores

minutiae

points of interest in a fingerprint, individuality of a fingerprint is determined by the careful study of its ridge characteristics

there are as many as 150 minutiae on the average finger

no predetermined minimum number of friction ridge characters which must be present in two impressions in order to establish positive identification in the US

ridge ending

a ridge that ends abruptly 

ridge bifurcation

single ridge that divides into two ridges

short ridges (island)

a ridge that commences, travels a short distance and then ends

enclosure

a single ridge that bifurcates and reunites shortly afterward to continue as a single ridgel

latent fingerprints

pores leading to sweat glands from which perspiration is deposited on the skin, along with oils that may have been picked up by touching the hairy portions of the body, is transferred onto that surface

factors affecting deposition of latent print

sweat, surface, contact, envrionment

processing problems

• condition of the surface and the limited smooth area available for processing

• superimposed or smudged because of the way an item of evidence is handled

• surface is dirty, oily, greasy

primary concern in all cases

for fingerprints not to add any other fingerprints or destroy the ones that may be present

when articles containing latents must be picked up, touch as little as possible, and then only in areas least likely to contain identifiable latents, such as rough surfaces

patent print

a print that is visible to the human eye

latent print

a print that is not visible to the human eye

four basic surface conditions

porous, non-porous, non-porous rough, special conditions

porous surface

paper, cardboard, untreated wood

non-porous smooth

painted, plastic, or glass surfaces

non-porous rough

vinyl, leather, textured coutertopsspe

special conditions

skin, adhesive tape

super glue fingerprinting

cyanoacrylate fuming is a technique that stabilizes latent prints

the object is expose d to fumes which harden the print and then the print is lifted in typical fashion

ninhydrin - reuhmann’s purple

reacts with amino acids to produce a purple-colored impression. Effective on a wide range of porous surfaces

need a fume hood or outdoor environment is a must, short shelf life, horrible smell

fuming

two different sides of tape used for adhesive surfaces this is the one best for the slick side

wet wop

two different sides of tape used for adhesive surfaces this is the one best for the sticky side

simple solution

mix black latent fingerprint powder with dish washing liquid into a pancake batter consistency then pour over sticky side, rinse with water

crime scene sketching

act of drawing a two dimensional view of the scene and important artifacts

graphically illustrates the layout, orientation and interrelationships

crime scene mapping

process of measuring and recording the associated locations of these elements in the scene

accurately measuring the position of every item depicted in the rough sketch

every item included in the rough sketch should be measured from one or more reference points

reference points

fixed points at the scene that can be used to reconstruct the scene even many years later

• power poles, light poles, sidewalk/driveway intersection

rectangular measurement reference points

only require two adjacent walls that create a right angle (the measurements must intersect)

five essential elements of the sketch

heading, diagram area, legend, title block, scale and direction notations

heading

a simple title that explains the purpose of the sketch (i.e. rough sketch depicting evidence and measurements)

diagram area

the actual sketch or drawing iteself

legend

annotations that explain any symbols used in the sketch

title block

administrative data, indicating case number, address of the location, date and time the sketch was prepared and by whom

scale and direction notations

annotations that indicate the direction north as depicted by the sketch and whether any scale was used

2D “birds-eye” view

standard crime scene sketch view that easily indicates items on a horizontal surface

cross projection sketch and elevation sketch

show additional details associated to vertical surfaces

cross projection sketch

combines both the “birds-eye” and elevation sketch

most common mapping methods

• baseline coordinates

• rectangular coordinates

• triangulation

baseline mapping

best used in exterior scenes with limited landmarks

line is extended from a datum point in a cardinal direction

a single measurement is made from the evidence to the line at a right angle

usually inappropriate for typical interior scenes

triangulation method

best utilized in scenes with evident landmarks

the most precise mapping method as it fixes regular shaped objects in a specific position

it is time intensive due to the measurements required

the number of measurements is based on whether the objects shape is regular or irregular

one measurement

number of measurements required for irregular objects these objects have no specific points or shapes that will change with movement (i.e. blood pools, clothing piles) need straight line measurements from two distinct landmarks to the center of mass on the item