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IAI CSSA practice questions

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Question 1Crime Scene Investigation

At a crime scene, which of the following best describes the primary purpose of establishing a controlled perimeter?

  1. To allow media representatives to record the scene from a fixed distance
  2. To provide a staging area for the transport of detained suspects
  3. To limit access and prevent contamination or loss of physical evidence Correct answer.
  4. To give first responders a place to conduct informal interviews with witnesses

Explanation

A perimeter is established to restrict access to the scene so that unauthorized persons cannot alter, destroy, or add material to the evidence. Controlling entry is the foundation of scene integrity and underpins every later documentation step.

Question 2Crime Scene Investigation

A crime scene investigator is documenting the scene. Which method provides the most complete permanent record of the overall scene layout before items are moved?

  1. An audio narration recorded by the first officer on arrival
  2. A sketched diagram prepared later from memory
  3. A systematic series of overlapping photographs covering the entire scene Correct answer.
  4. A single close-up photograph of the most significant item

Explanation

Systematic overlapping photographs create a comprehensive visual record that shows the scene as found and preserves spatial relationships. This must be completed before any evidence is collected or moved.

Question 3Crime Scene Investigation

Which of the following is the correct sequence for processing a crime scene?

  1. Collection, documentation, recognition, and preservation
  2. Documentation, preservation, collection, and recognition
  3. Preservation, collection, recognition, and documentation
  4. Recognition, documentation, collection, and preservation Correct answer.

Explanation

Evidence must first be recognized, then documented in place, then collected, and finally preserved for later analysis. Documentation before collection preserves the context and position of each item.

Question 4Crime Scene Investigation

During a search of a burglary scene, an investigator finds a latent fingerprint on a glass surface. Which collection method is most appropriate?

  1. Swabbing the print with a wet cotton swab
  2. Lifting the print with adhesive tape after powder development Correct answer.
  3. Scraping the print into a paper envelope
  4. Cutting the entire glass pane out and discarding the print

Explanation

Latent prints on non-porous surfaces are typically developed with powder and lifted with adhesive tape onto a backing card. This preserves ridge detail for comparison.

Question 5Crime Scene Investigation

An investigator needs to preserve a bloodstained shirt for DNA analysis. Which action best maintains the integrity of the sample?

  1. Wash the shirt and then package it in a sealed container
  2. Store the shirt in direct sunlight to accelerate drying
  3. Seal the shirt in a plastic bag while still damp
  4. Allow the shirt to air-dry and package it in a paper bag Correct answer.

Explanation

Biological evidence should be air-dried and packaged in breathable paper to prevent moisture buildup and degradation. Plastic packaging of damp items promotes bacterial growth and DNA breakdown.

Question 6Crime Scene Investigation

Which of the following best explains why chain of custody documentation is essential for physical evidence?

  1. It establishes an unbroken record of who handled the evidence and when Correct answer.
  2. It confirms that the evidence was collected by a sworn officer
  3. It replaces the need for laboratory analysis of the item
  4. It records the investigator's opinion about the suspect's guilt

Explanation

Chain of custody is a chronological record of every person who handled the evidence and every transfer of control. It demonstrates that the item is the same one collected and has not been tampered with.

Question 7Crime Scene Investigation

A crime scene investigator must decide whether to use a flashlight or a laser to locate trace evidence. Which statement best describes an appropriate use of oblique lighting?

  1. Directing a bright beam straight down to bleach out shadows on the floor
  2. Holding a light source at a low angle to reveal surface irregularities and latent impressions Correct answer.
  3. Using ultraviolet light to illuminate the entire room evenly
  4. Placing the light behind the investigator to maximize glare on surfaces

Explanation

Oblique lighting is directed across a surface at a low angle so that texture, dust, and latent impressions cast shadows and become visible. It is a standard search technique for trace and impression evidence.

Question 8Crime Scene Investigation

When photographing a crime scene, why should a scale be included in close-up photographs of evidence?

  1. To indicate the direction of north in the photograph
  2. To obscure identifying features of the item
  3. To provide a reference for the size and dimensions of the item Correct answer.
  4. To show the investigator's case number in the image

Explanation

A scale provides a known reference so that the actual size and dimensions of the evidence can be determined from the photograph. It supports accurate measurement and later reconstruction.

Question 9Crime Scene Investigation

An investigator is documenting a bloodstain pattern on a wall. Which documentation combination most strongly supports later pattern analysis?

  1. A written description without photographs or measurements
  2. A photograph taken after the wall has been cleaned
  3. Close-up photographs with a scale plus measured distances to reference points Correct answer.
  4. A single wide photograph of the room

Explanation

Pattern analysis depends on accurate size, shape, and spatial relationships, which require close-up scaled photographs and measured reference distances. This allows the analyst to reconstruct the geometry of the event.

Question 10Crime Scene Investigation

Which of the following describes the correct technique for collecting a questioned document found at a scene?

  1. Fold the document along its existing creases and staple it to a report
  2. Handle it minimally, place it in a protective sleeve, and avoid adding marks Correct answer.
  3. Laminate the document to preserve it permanently
  4. Write the case number directly on the face of the document

Explanation

Questioned documents must be handled minimally to avoid adding fingerprints, folds, or marks that could be mistaken for evidence. A protective sleeve preserves condition during transport.

Question 11Crime Scene Investigation

During a scene search, an investigator finds a footwear impression in soft soil. Which action best preserves this evidence?

  1. Fill the impression with water to stabilize it
  2. Cover the impression with a heavy board and walk over it
  3. Photograph the impression and leave it unprotected
  4. Pour plaster or casting material directly into the impression after removing loose debris Correct answer.

Explanation

A footwear impression in soil is preserved by careful casting, after loose debris is removed and the impression is photographed. The cast captures three-dimensional detail for comparison.

Question 12Crime Scene Investigation

Which statement best describes the role of a crime scene sketch in relation to photographs?

  1. The sketch should be prepared only after the trial begins
  2. The sketch replaces photographs because it is more objective
  3. The sketch supplements photographs by showing measured spatial relationships Correct answer.
  4. The sketch is optional and has no evidentiary value

Explanation

A sketch complements photographs by providing measured distances and a clear spatial layout that photographs alone cannot convey precisely. Together they give a more complete record of the scene.

Question 13Crime Scene Investigation

An investigator suspects a fire was intentionally set. Which observation most directly supports an origin-and-cause investigation?

  1. The presence of smoke damage on the ceiling
  2. Charring patterns indicating multiple separate points of origin Correct answer.
  3. The smell of smoke in adjacent rooms
  4. Water damage from firefighting operations

Explanation

Multiple separate points of origin are a recognized indicator of an intentionally set fire. Origin-and-cause analysis looks for patterns that cannot be explained by a single accidental source.

Question 14Crime Scene Investigation

Which of the following best explains why investigators should avoid excessive movement within a crime scene?

  1. Movement helps investigators locate evidence more quickly
  2. Movement has no effect on the evidentiary value of the scene
  3. Movement is prohibited only in outdoor scenes
  4. Movement can introduce foreign trace material and disturb existing evidence Correct answer.

Explanation

Excessive movement risks transferring fibers, hairs, and other trace material and can displace or destroy evidence. Controlled movement along a documented path protects scene integrity.

Question 15Crime Scene Investigation

A latent print is found on a porous surface such as paper. Which development approach is generally most suitable?

  1. Chemical treatment such as ninhydrin Correct answer.
  2. Superglue fuming followed by casting
  3. Powder dusting followed by tape lift
  4. Casting with dental stone

Explanation

Porous surfaces absorb the print residue, so chemical reagents such as ninhydrin are used to develop latent prints on paper. Powders work on non-porous surfaces where residue remains on the surface.

Question 16Crime Scene Investigation

Which of the following is the most appropriate way to package a firearm recovered at a crime scene?

  1. Place it in a sealed plastic bag with the magazine removed
  2. Wrap it in cloth and place it in a sealed container without a tag
  3. Attach an evidence tag to the trigger guard and package in a paper box Correct answer.
  4. Unload it and place it loose in the investigator's pocket

Explanation

Firearms are typically secured with an evidence tag and placed in a rigid paper container that allows ventilation and protects the item. This preserves potential latent prints and trace evidence while preventing moisture buildup.

Question 17Crime Scene Investigation

An investigator is deciding how to collect a dried blood flake from a hard surface. Which method is most appropriate?

  1. Press adhesive tape directly onto the flake and discard the tape
  2. Dissolve the flake in a large volume of water
  3. Scrape the flake with a clean instrument onto a paper bindle Correct answer.
  4. Wipe the surface with a dry cloth and discard the cloth

Explanation

Dried blood flakes can be carefully scraped onto a clean paper bindle, which preserves the sample for DNA analysis. The bindle is then sealed and documented.

Question 18Crime Scene Investigation

Which of the following best describes the purpose of a control sample at a crime scene?

  1. To replace the need for a chain of custody
  2. To confuse the analysis and test the investigator's skill
  3. To serve as a substitute for the questioned sample
  4. To provide a known reference against which questioned samples can be compared Correct answer.

Explanation

A control sample is a known reference material collected from the scene or a known source so that questioned samples can be compared against it. It helps distinguish evidentiary material from background material.

Question 19Crime Scene Investigation

At a homicide scene, an investigator observes a spent cartridge case on the floor. Which documentation step should occur before the case is collected?

  1. Pick up the case and place it in a pocket for safekeeping
  2. Photograph the case in place with a scale and record its location Correct answer.
  3. Kick the case aside to clear a walking path
  4. Wait until the laboratory requests the case

Explanation

The cartridge case must be documented in its original position with scaled photographs and a recorded location before it is moved. Positional context is essential to reconstructing the shooting.

Question 20Crime Scene Investigation

Which of the following statements about the use of a search pattern at a crime scene is most accurate?

  1. Only one search pattern is ever appropriate for any scene
  2. Search patterns are unnecessary if the scene is small
  3. Search patterns are used only for outdoor scenes
  4. The choice of pattern depends on the scene size, layout, and available personnel Correct answer.

Explanation

Investigators select a search pattern based on factors such as scene size, layout, and the number of personnel available. The goal is systematic coverage that minimizes missed evidence.

Question 21Crime Scene Investigation

An investigator finds a partially burned accelerant container. Which action best preserves potential accelerant residue?

  1. Seal the container in an airtight metal can and document it Correct answer.
  2. Leave the container open to the air for several days
  3. Wash the container to remove soot
  4. Place the container in a paper bag with holes

Explanation

Accelerant residue is volatile, so the container should be sealed in an airtight metal can to prevent evaporation and preserve the sample for laboratory analysis. Documentation accompanies the sealed item.

Question 22Crime Scene Investigation

Which of the following best describes why a crime scene investigator should record the environmental conditions at the scene?

  1. Conditions are relevant only to traffic accident scenes
  2. Conditions have no bearing on the interpretation of evidence
  3. Conditions such as temperature and weather can affect the degradation of evidence Correct answer.
  4. Conditions are recorded only to complete paperwork

Explanation

Temperature, humidity, and weather can influence the condition and degradation of biological and trace evidence. Recording these conditions helps analysts interpret the evidence correctly.

Question 23Crime Scene Investigation

An investigator is asked to collect a control sample of soil near a questioned soil stain. Why is this control important?

  1. It provides a comparison to distinguish the questioned soil from the surrounding soil Correct answer.
  2. It confirms the investigator's identity
  3. It measures the temperature of the soil
  4. It replaces the need to collect the questioned sample

Explanation

A soil control from the immediate area allows the laboratory to compare the questioned sample against the background soil. This comparison helps determine whether the questioned soil is foreign to the location.

Question 24Crime Scene Investigation

Which of the following best describes the concept of scene reconstruction?

  1. The process of returning evidence to its original position after analysis
  2. The process of rebuilding a damaged structure at the scene
  3. The process of interviewing witnesses to obtain a confession
  4. The process of forming a hypothesis about events based on evidence and scene analysis Correct answer.

Explanation

Scene reconstruction uses the physical evidence, documentation, and analysis to develop a hypothesis about what happened and in what sequence. It is an interpretive process grounded in evidence, not physical rebuilding.

Question 25Crime Scene Investigation

An investigator finds a hair with a root attached at a scene. Which statement best explains why the root is significant?

  1. The root may contain nuclear DNA suitable for profiling Correct answer.
  2. The root makes the hair unsuitable for any analysis
  3. The root prevents the hair from being photographed
  4. The root indicates the hair was cut rather than shed

Explanation

A hair with an attached root can contain nuclear DNA, which is more discriminating than mitochondrial DNA from the shaft. This makes the root valuable for identification.

Question 26Crime Scene Investigation

Which statement best describes the primary purpose of securing a crime scene perimeter before evidence collection begins?

  1. To speed up the investigation by allowing all responders to work simultaneously
  2. To ensure neighbors can observe the investigation for transparency
  3. To allow media representatives to record the scene from a controlled distance
  4. To prevent contamination and loss of evidence by limiting access to authorized personnel Correct answer.

Explanation

A perimeter exists to protect the integrity of the scene by excluding unauthorized persons and controlling the movement of those who must enter. Uncontrolled access introduces transfer, loss, and alteration of evidence. Everything else at the scene depends on this initial control.

Question 27Crime Scene Investigation

An investigator arrives at a scene where a body lies near an overturned table. Which action should be taken first to preserve the scene as found?

  1. Collect the victim's clothing before documenting the room
  2. Move the body to a cooler area to slow decomposition
  3. Right the table so the body can be photographed clearly
  4. Record the scene photographically before anything is moved Correct answer.

Explanation

The scene must be documented in its original condition before any alteration, because photographs and notes of the undisturbed arrangement are irreplaceable. Moving or righting objects destroys positional relationships. Collection follows documentation.

Question 28Crime Scene Investigation

Which of the following is the most appropriate first action when a responder discovers a suspected explosive device at a scene?

  1. Cut the visible wires to render the device safe
  2. Carry the device to an isolated area for disposal
  3. Evacuate and secure the area and request bomb squad assistance Correct answer.
  4. Photograph the device from close range for identification

Explanation

Suspected explosive devices are handled only by trained bomb disposal personnel. The responder's role is to isolate the hazard by evacuating and securing the area and summoning specialists. Any physical interference risks detonation.

Question 29Crime Scene Investigation

Which piece of personal protective equipment is most important for preventing investigator DNA from contaminating biological evidence?

  1. A high-visibility vest
  2. Disposable gloves changed between items Correct answer.
  3. A reflective armband
  4. Steel-toed boots

Explanation

Gloves act as a barrier between the investigator's skin cells and biological evidence, and changing them between items prevents cross-transfer. Other listed items address physical safety or visibility, not biological contamination. Consistent glove discipline is fundamental.

Question 30Crime Scene Investigation

Which of the following best describes the purpose of a rough sketch made at the crime scene?

  1. To provide a finished courtroom exhibit ready for presentation
  2. To document the investigator's opinions about what occurred
  3. To record measurements and spatial relationships for later use Correct answer.
  4. To replace photographs when lighting is poor

Explanation

A rough sketch captures dimensions, distances, and the relative positions of items while the investigator is still at the scene. It is a working record from which a finished diagram may later be produced. It supplements rather than replaces photographs.

Question 31Crime Scene Investigation

An investigator finds a wet, bloodstained garment at a scene. Which packaging approach best preserves it?

  1. Place it in a paper bag or box and allow it to air-dry Correct answer.
  2. Seal it in a plastic bag immediately while still damp
  3. Place it in a sealed glass jar with a desiccant
  4. Fold the stained area inward and tape it closed

Explanation

Damp biological evidence sealed in plastic can grow mold and degrade DNA, so it must be packaged in breathable material and dried. Paper bags or boxes allow moisture to escape. Once dry, the item can be sealed for transport.

Question 32Crime Scene Investigation

Which of the following best describes the purpose of a photo log or photographic record sheet at a crime scene?

  1. To link each photograph to its location, subject, and sequence Correct answer.
  2. To record the cost of photographic supplies used
  3. To certify that the photographer is a sworn officer
  4. To list the names of all persons present at the scene

Explanation

A photo log ties each exposure to what it depicts, where it was taken, and the order in which it was made, which supports later authentication. It is a documentation tool, not a personnel or expense record. This linkage is what makes photographs usable in court.

Question 33Crime Scene Investigation

Which of the following is the most appropriate way to mark a location where evidence was recovered after the item has been collected?

  1. Ask a bystander to stand at the location
  2. Leave a piece of the evidence behind as a marker
  3. Place a numbered or lettered evidence marker at the spot Correct answer.
  4. Rely on memory and describe the location verbally later

Explanation

Evidence markers preserve the recorded position of an item after removal and link the location to photographs and the evidence log. They maintain a consistent reference system throughout documentation. Memory and bystanders are unreliable substitutes.

Question 34Crime Scene Investigation

An investigator needs to collect a questioned sample of paint chips from a wall that may have been struck during an incident. Which collection approach is most appropriate?

  1. Scrape the entire wall area into one container
  2. Use adhesive tape to lift the chips and leave the tape attached to the wall
  3. Discard the chips because paint is not physical evidence
  4. Collect the chips with clean tools into a labeled container and also take a known sample from the damaged area Correct answer.

Explanation

Paint chips should be collected with clean tools into a labeled container, and a known sample from the damaged area provides a comparison standard. Collecting the questioned and known samples separately preserves their value for comparison. Paint is indeed a recognized type of physical evidence.

Question 35Crime Scene Investigation

A footwear impression in dry dust on a hard floor is discovered. Which method best preserves and documents this impression?

  1. Wet the area to stabilize the dust before photographing
  2. Wipe the floor clean and rely on the photographs
  3. Vacuum the area to collect the dust for analysis
  4. Photograph it with a scale and lift it with an electrostatic dust lifter Correct answer.

Explanation

Dry-residue impressions on hard surfaces are documented photographically with a scale and then lifted, commonly with an electrostatic dust lifter that transfers the pattern to a film. Wetting destroys the pattern. Vacuuming and wiping destroy the impression entirely.

Question 36Crime Scene Investigation

An investigator is documenting a scene where a window was broken and glass fragments are scattered both inside and outside. Which observation most directly helps establish the direction of the breaking force?

  1. The distribution of glass fragments and the presence of radial and concentric fracture patterns Correct answer.
  2. The temperature of the room at the time
  3. The brand name printed on the window frame
  4. The color of the glass fragments

Explanation

Fracture patterns and fragment distribution help analysts infer the direction and point of impact. Radial and concentric fractures have characteristic relationships to the impact side. Fragment scatter can also indicate whether breaking force came from inside or outside.

Question 37Crime Scene Investigation

A questioned bloodstain is found on a suspect's shoe, and the investigator wishes to determine whether it could have come from the victim. Which comparison is most relevant?

  1. Comparing the color of the shoe to the color of the victim's clothing
  2. Comparing the DNA profile from the stain to a known reference sample from the victim Correct answer.
  3. Comparing the shoe's tread pattern to the victim's footwear
  4. Comparing the shoe size to the victim's shoe size

Explanation

DNA profiling of the stain against a known reference from the victim can establish whether the biological material is consistent with that source. The other comparisons address unrelated attributes. Source attribution of biological stains rests on genetic comparison.

Question 38Crime Scene Investigation

An investigator observes a bloodstain pattern consisting of many small droplets radiating outward from a central area on a wall. Which interpretation is most consistent with this pattern?

  1. The pattern demonstrates that the blood was diluted with water
  2. The pattern indicates a single passive drip from a stationary source
  3. The pattern is consistent with an impact that produced a mist of droplets Correct answer.
  4. The pattern proves the blood was transferred by contact with a bloody object

Explanation

A radiating spray of fine droplets is characteristic of an impact event that aerosolizes blood. Passive drips produce larger, often circular stains, and contact transfer produces smears or transfers rather than a radiating mist. Interpretation must remain consistent with the observed droplet size and distribution.

Question 39Crime Scene Investigation

Which of the following best explains why investigators should document the position of furniture and objects in relation to the body at a homicide scene?

  1. To establish the resale value of the furnishings
  2. To determine which items should be returned to the owner first
  3. To confirm the identity of the responding officers
  4. To help reconstruct movement and events and to test witness accounts Correct answer.

Explanation

Spatial relationships between the body and surrounding objects support reconstruction of events and can corroborate or contradict witness statements. Positional documentation captures information that cannot be recovered once items are moved. It has nothing to do with property value or personnel.

Question 40Crime Scene Investigation

An investigator finds a latent fingerprint on a nonporous glass surface. Which development technique is generally most suitable?

  1. Ninhydrin spraying
  2. Powder dusting or cyanoacrylate fuming Correct answer.
  3. Iodine fuming followed by silver nitrate
  4. Physical developer immersion

Explanation

Nonporous surfaces such as glass retain latent prints that respond well to powder dusting or cyanoacrylate (superglue) fuming. Ninhydrin and physical developer are typically used on porous surfaces. Matching the technique to surface type is essential.

Question 41Crime Scene Investigation

A questioned bullet is recovered from a wall. Which handling practice best preserves the evidence for firearms examination?

  1. Wrap it in a soft cloth, package it separately, and label it without marking the bearing surfaces Correct answer.
  2. Clean it with solvent to remove debris
  3. Hold the bullet with forceps at the base and mark it with a scribe
  4. Roll it in a single container with other bullets

Explanation

The striated bearing surfaces of a bullet carry the marks used for comparison, so they must not be scratched or marked. Wrapping the bullet and packaging it separately protects these surfaces. Cleaning or co-mingling can destroy or confuse the evidence.

Question 42Crime Scene Investigation

During a scene search, an investigator finds a small plastic bag containing a white powder. Which action is most appropriate?

  1. Dissolve the powder in water to test for solubility
  2. Taste a small amount to identify the substance
  3. Package the bag as found, label it, and submit it for laboratory analysis Correct answer.
  4. Dispose of the bag because it is not relevant

Explanation

Unknown substances are hazardous and are identified by laboratory analysis, not field tasting. The item should be packaged and labeled intact and submitted through the proper chain of custody. Field testing of unknown powders risks exposure.

Question 43Crime Scene Investigation

Which of the following best explains why investigators should use a systematic search pattern rather than a random walk when searching a large outdoor area?

  1. A systematic pattern removes the need for documentation
  2. A systematic pattern reduces the chance that an area is skipped or searched twice Correct answer.
  3. A random walk allows investigators to cover more ground quickly
  4. A random walk ensures that all investigators search the same area

Explanation

Systematic patterns such as line, grid, or spiral searches provide consistent coverage and reduce the chance of missed or duplicated areas. Random movement is unreliable for thorough coverage. Documentation is still required regardless of search method.

Question 44Crime Scene Investigation

An investigator recovers a partially burned piece of fabric near a suspected fire origin. Which action best preserves it for laboratory analysis?

  1. Seal it in an airtight metal can or approved fire debris container Correct answer.
  2. Place it in an open paper envelope and leave it in the sun
  3. Wash it with water to remove soot
  4. Discard it because burned fabric has no evidentiary value

Explanation

Fire debris may contain volatile accelerant residues that can escape from permeable or open packaging. Airtight metal cans or approved containers preserve these residues for analysis. Washing or discarding the fabric destroys the evidence.

Question 45Crime Scene Investigation

An investigator must collect a control sample of carpet from an area adjacent to a burned patch. Which statement best explains why this control is needed?

  1. It shows what the burned area would have looked like if it had not burned
  2. It replaces the need for laboratory analysis
  3. It provides a comparison for background materials that may be present in the questioned sample Correct answer.
  4. It proves the fire was intentionally set

Explanation

A control sample from an unaffected adjacent area establishes the background composition of the material so that analysts can distinguish residues present naturally from those introduced. It does not by itself establish intent. Laboratory analysis remains necessary.

Question 46Crime Scene Investigation

Which of the following best describes the appropriate response when an investigator discovers that a piece of evidence was inadvertently moved before being photographed?

  1. Recreate the original position and photograph it as though it had not been moved
  2. Document the alteration, the current condition, and the circumstances in the notes Correct answer.
  3. Omit the evidence from the report to avoid confusion
  4. Discard the item because its value is lost

Explanation

Honest documentation of an alteration, including what happened and who was involved, preserves the credibility of the record. Recreating positions fabricates evidence, and omission or destruction conceals facts. Transparency is the professional standard.

Question 47Crime Scene Investigation

A scene contains a computer that appears to be powered on. Which action best preserves potential digital evidence?

  1. Delete recent files to protect the owner's privacy
  2. Unplug the computer and remove the hard drive
  3. Shut down the computer immediately to prevent changes
  4. Photograph the screen, leave the system running, and consult a digital evidence specialist Correct answer.

Explanation

Powering down or altering a running system can destroy volatile data and alter timestamps. The initial response is to document the visible state and involve a digital evidence specialist who can capture volatile information properly. Deleting files is destructive and improper.

Question 48Crime Scene Investigation

An investigator is reconstructing a shooting in which a bullet passed through a window and struck an interior wall. Which combination of scene observations best supports estimating the bullet's path?

  1. The color of the window frame and the wall paint
  2. The number of witnesses and the distance to the street
  3. The hole in the glass, the hole in the wall, and the recovered projectile Correct answer.
  4. The time of day and the outdoor temperature

Explanation

Trajectory reconstruction relies on the physical features of the perforations and the recovered projectile, which together define a line through space. Environmental and witness factors may provide context but do not define the path. Physical evidence anchors the reconstruction.

Question 49Crime Scene Investigation

An investigator finds a single hair with a root attached on a victim's clothing and a second hair without a root nearby. Which statement best explains the differing evidentiary significance?

  1. The hair without a root is always more probative because it is older
  2. Neither hair can be analyzed because hair is not biological evidence
  3. Both hairs are equally suitable for nuclear DNA analysis
  4. The hair with a root may yield nuclear DNA suitable for comparison, while the hair without a root may be suitable only for mitochondrial DNA analysis Correct answer.

Explanation

A root contains follicular tissue that can provide nuclear DNA, whereas a shed hair shaft generally lacks nuclear DNA but may contain mitochondrial DNA. The two hairs therefore differ in the type of genetic information they can yield. Hair is a recognized form of biological evidence.

Question 50Crime Scene Investigation

An investigator must decide whether a death scene should be treated as a homicide or an accident. Which approach is most consistent with sound scene methodology?

  1. Treat the scene as a potential homicide until evidence and investigation indicate otherwise, while collecting all available evidence Correct answer.
  2. Wait for a confession before documenting the scene
  3. Rely solely on the initial responding officer's impression
  4. Assume an accident unless a weapon is visible

Explanation

Premature classification can cause investigators to overlook or discard evidence that later proves important, so scenes are treated as potential homicides until the evidence supports another conclusion. Assumptions based on a single observation or a confession are unreliable. Comprehensive collection preserves options.