Forensic Bio Unit 1

question

What are the key questions that must be answered at each crime scene?
answer

WHO was the victim/intended victim, perp & witnesses WHAT were the events that led up to the crime, motive, modus operandi, tools, objects removed from scene WHEN did crime occur, key events that led up to crime WHERE did crime occur, perp enter/leave scene, perp stand during commission of crime, people within the scene, witnesses stand, victim found
question

Preserving the crime scene includes taking what precautions?
answer

protective white suits closing body bags shoe covers gloves masks metal platforms laid out/common approach pathway *volume crimes such as burglaries do not require as much contamination prevention restrict access to scene, monitor who comes & goes and when
question

recording the crime scene the way it was found includes what?
answer

notes, photos (note location of photo, who took it, direction camera was pointing, date/time image was capture & lighting conditions), video, sketches (useful for pathology to see how victim was found & to see if pieces of evidence were removed)
question

what is the procedure for dealing with fingerprints?
answer

photograph fingerprint FIRST then decide whether to dust or swab – swabbing the fingerprint for DNA evidence will essentially destroy it
question

responsibilities of first responding officer
answer

determine if crime scene is safe (is crime still in progress? if so, they must resolve it by taking perp into custody) initial scene assessment to see if it’s safe & if anyone needs medical attention (must keep witnesses alive!) identify eye witnesses – separate them from the scene & from each other try to obtain statements as quickly as possible while memories are fresh call for assistance (will vary depending on complexity of scene) restrict access to scene (to prevent contamination as well as to reduce accusations of tampering with evidence – may involve sealing off front door & having officer stand guard to monitor those entering/exiting) log of action (time table of all actions which occur after 1st officer arrives on scene; can be important in court when questioned about when officers arrived on scene, experts present on scene, can prove scene was restricted & evidence wasn’t tampered with)
question

method of search/recovery of physical evidence depends on what?
answer

type of crime (volume vs. serious) collecting evidence from volume crimes typically includes high quality evidence in areas that have been clearly disturbed (along route perp has taken thru crime scene such as entry, exit, areas where items were stolen). In volume crimes you are mostly looking for fingerprints & DNA samples – not a lot of evidence, just enough to identify perp
question

Serious crimes, which require as much evidence as can possibly be recovered, may utilize what search patterns?
answer

inward-spiral pattern outward-spiral pattern zone pattern parallel pattern grid pattern
question

Which search patterns are best to use when only a single officer is present?
answer

inward-spiral (begin at perimeter & make smaller & smaller inward spirals toward center of scene) outward-spiral (start at center – maybe where victim’s body is present – and make spiral patterns outward toward perimeter)
question

What search pattern is best to use when more than 1 officer is present?
answer

zone pattern (scene is divided into zones & each zone examined by an officer)
question

What search patterns are best to use when the crime scene is large, such as a field?
answer

parallel pattern (multiple officers line up & walk in parallel across crime scene) grid pattern (2 parallel searches, each occurring in different directions)
question

pattern of search depends on what?
answer

type of crime, size of crime scene, # of people present at scene & what evidence you’re expecting to find
question

How is blood spatter evidence recorded?
answer

photo of spatter examine pattern at the scene or take it to the lab (if spatter is on something such as a t-shirt or piece of furniture) blood spatter expert will interpret pattern genetics expert may take sample of blood for DNA analysis – only after interpretation is complete so as to not disrupt the pattern
question

How are fingerprints recorded?
answer

dusting will enhance the print, which can then be lifted with some kind of tape it is important to prioritize fingerprinting, as DNA may be extracted from a single cell – thus can be extracted from a fingerprint
question

how are footprint/shoeprint evidence recorded?
answer

shoeprints aren’t unique to a person, but might be helpful if compared to the suspect’s sole – which can reduce # of suspects
question

How is drug evidence recorded?
answer

substance must be identified via a \”presumptive\” test on the scene – after which it must be sent to a lab to confirm whether substance is illegal
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how is gun evidence recorded?
answer

A gun may be used for ballistic analysis of bullets fired, fingerprints on gun, find out if it was recently fired, comparison of bullets at crime scene vs those in gun
question

How is evidence packaged & labelled?
answer

each article is stored separately to avoid cross-contamination each item must be stored using evidence bags & tags maintain chain of custody by recording who collected evidence, where it was collected, when collected, and offense it is related to
question

How must small evidence (such as hairs/fibers) be packaged?
answer

in a sealed envelope, then put in a larger evidence bag
question

how must dry clothing/shoes be stored?
answer

paper bag
question

how must wet clothing be packaged?
answer

either dried first, or stored in a plastic bag kept in a freezer to prevent mold growth – mold would damage the evidence
question

how must evidence contaminated by hydrocarbon fuel (such as petroleum/gas) be packaged?
answer

in a nylon bag tied with a special knot which creates an airtight seal
question

crime scenes include what?
answer

site of offense victim suspect homes of witnesses, victims & suspects *all crime scenes must be processed in the same manner
question

T or F The very first walk thru of a crime scene by a first attending officer involves a search to locate possible items of evidence.
answer

FALSE The initial walk thru is to establish health & safety, to determine if the scene is safe to enter & see if there is anyone present on the scene who needs medical assistance
question

Locard’s exchange principle implies all of the following EXCEPT: Soil samples can be carried from the yard into your home. Fibers can be transferred from one person to another. Cat hair can be transferred to your pants. Blood spatter can be used to identify blood type.
answer

Blood spatter can be used to identify blood type. ^This answer is not related to Locard’s exchange principle. It states that every contact leaves a trace.
question

3 police officers are asked to search a large field for evidence. Which search pattern would be LEAST helpful for this search? Grid, spiral, zone or parallel lines
answer

Spiral ^This type of search usually only involves one person & should be conducted in small areas.
question

Is a bomb blast an example of a volume crime?
answer

NO it is a serious crime
question

Correct collection of evidence requires what?
answer

Documenting the location where the evidence was found Correct packaging of evidence Maintaining proper chain of custody
question

What is \”chain of custody?\”
answer

It is associated with each item of evidence & lists the signatures & dates of people who have been in contact with the evidence. The chain of custody is important because it helps prove the evidence hasn’t been tampered with.
question

One early summer’s morning, a man who is walking his dog discovers a dead body in a field along a public footpath. The weather is warm & sunny but there has been recent rain & more is forecasted. A brief inspection reveals that the victim is quite clearly dead and appears to have suffered multiple stab wounds. The man calls 911 on his cell phone to request police. The first reporting officer arrives, followed shortly by the crime scene analysts. Describe 2 different methods you could use to record this crime scene & discuss the benefits/limitations of both.
answer

Photographs could be used to record the crime scene. The benefit is that _ & the limitations are _ Sketches can be used to record the crime scene as well. The benefits are _ & the limitations are _
question

At the scene of a crime, the evidence collector found a damp bloody shirt. He quickly wraps the shirt in a paper bag. He inserted the bag into an evidence bag, sealed it with tape & wrote his name across the tape. The evidence collection log was completed and taped to the bag. What did he do incorrectly?
answer

Because the shirt had blood on it, it should have been photographed prior to packaging. A clear picture of the blood spatter may aid the blood spatter analyst’s interpretation. Because the shirt was damp, it should not be stored in a paper bag. This could promote mold growth which could damage the evidence. Instead it should have first been dried or stored in a plastic bag in a freezer or refrigerator to prevent mold growth.
question

The 1st stage in an investigation is to preserve the crime scene. Why is this so important for the rest of the investigation?
answer

Preserving the crime scene is crucial, because without this step a case cannot be made to try before a judge. Preserving the scene prevents contamination of the scene, tampering with/removal of evidence and accurate testimonies from witnesses. Part of preserving the scene involves identifying eye witnesses & immediately separating them from each other & from the scene. This allows accurate testimony to be made without influence from other witnesses or the state of the scene. If inside, an officer may guard the door of a scene & record who enters & exits. This prevents the prosecution/defense from making accusations of evidence tampering. Lastly, if the scene is outside or if bad weather is impending, preserving the scene is a necessity to gathering all evidence & maintaining its integrity.
question

Which evidence could be used as probative evidence in a courtroom (prosecution wants to prove that professor plum stabbed colonel mustard in the conservatory)? The only fingerprint found on the dagger used to murder him matches that of professor plum. A report from a forensic scientist stating that DNA could not be collected from the dagger. Evidence that colonel mustard & professor plum had dinner the week before. All the above.
answer

The only fingerprint found on the dagger used to murder him matches that of professor plum. ^Probative evidence provides support to one side of the case, either supporting the prosecution or defense.

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