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IAI SP9 practice questions

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Question 1Bloodstain Pattern

In bloodstain pattern analysis, what does the term 'angle of impact' describe?

  1. The angle between the victim's body and the floor when the blood was shed
  2. The angle of the weapon swing that produced cast-off
  3. The angle between two intersecting blood trails on a wall
  4. The angle between the blood droplet's flight path and the target surface at the moment of contact Correct answer.

Explanation

The angle of impact is the acute angle formed between the direction of droplet travel and the plane of the target surface at contact. It is derived from the shape of the resulting stain, which becomes more elongated as the angle decreases. This value is fundamental to reconstructing the three-dimensional origin of a spatter pattern.

Question 2Bloodstain Pattern

A bloodstain is circular with a diameter of 8 mm. What is the approximate angle of impact?

  1. 90 degrees Correct answer.
  2. 30 degrees
  3. 45 degrees
  4. 60 degrees

Explanation

A circular stain indicates that the droplet struck the surface perpendicular to the plane, meaning the impact angle is approximately 90 degrees. As the angle of impact decreases, the stain lengthens into an ellipse. Only a perpendicular strike produces a circular stain.

Question 3Bloodstain Pattern

Which formula is used to calculate the angle of impact from a bloodstain?

  1. Cosine of the angle equals stain length divided by stain width
  2. Tangent of the angle equals stain width divided by stain length
  3. Sine of the angle equals stain length divided by stain width
  4. Sine of the angle equals stain width divided by stain length Correct answer.

Explanation

The angle of impact is calculated using the relationship sine(angle) = width/length of the stain. The width is measured across the minor axis and the length along the major axis. The inverse sine of that ratio gives the impact angle, which approaches 90 degrees as the ratio approaches 1.

Question 4Bloodstain Pattern

What is the defining characteristic of a passive bloodstain?

  1. It results from blood expelled during respiration
  2. It is created when blood is projected under pressure
  3. It is formed solely by the force of gravity acting on the blood Correct answer.
  4. It is produced by a force applied to a blood source

Explanation

Passive bloodstains form when gravity alone moves the blood until it contacts a surface, without additional applied force. Dripping, pooling, and flow patterns are typical examples. Patterns involving applied force or pressure are classified differently.

Question 5Bloodstain Pattern

A series of bloodstains on the floor decrease progressively in size in a straight line. This pattern is best described as what?

  1. An expirated pattern
  2. A swipe pattern
  3. A cast-off pattern
  4. A drip trail Correct answer.

Explanation

A drip trail consists of passive bloodstains from blood falling under gravity as a bleeding person or object moves. The decreasing size along a line reflects a diminishing blood source or increasing distance from the surface. The linear arrangement and passive origin distinguish it from force-driven patterns.

Question 6Bloodstain Pattern

What is a transfer bloodstain pattern?

  1. A pattern created when blood flows downward under gravity
  2. A pattern created when blood accumulates in a pool
  3. A pattern created when blood is propelled by a force into small droplets
  4. A pattern created when a blood-bearing object contacts a surface and leaves an impression Correct answer.

Explanation

Transfer patterns occur when a wet, blood-bearing object is pressed against or drawn across a surface, leaving an image or contact mark. The resulting stain reflects the shape or texture of the object. This distinguishes transfer from spatter, flow, and pooling.

Question 7Bloodstain Pattern

Which statement best describes the mechanism that produces cast-off bloodstain patterns?

  1. Blood is drawn across a surface by a moving object
  2. Blood is flung from a blood-bearing object as it swings and decelerates Correct answer.
  3. Blood drips from a stationary wound onto the floor
  4. Blood is forced from the airway during exhalation

Explanation

Cast-off patterns result when a blood-covered object, such as a weapon, is swung and then decelerates, causing blood to be shed tangentially. The droplets travel in the direction of the swing and strike nearby surfaces, often producing linear arrangements. The pattern indicates the number of swings and the general direction of motion.

Question 8Bloodstain Pattern

An expirated bloodstain pattern is produced by which mechanism?

  1. Blood projected from a wound by a blunt-force impact
  2. Blood forced from the nose or mouth by airflow during breathing or coughing Correct answer.
  3. Blood transferred from a bloody hand onto a wall
  4. Blood shed from a swinging weapon

Explanation

Expirated patterns arise when blood in the airway or mouth is expelled by air pressure during breathing, coughing, or sneezing. The resulting stains are often fine and may show bubble rings or diluted appearance from mixing with saliva. This mechanism distinguishes expirated patterns from impact spatter.

Question 9Bloodstain Pattern

What does the term 'area of convergence' refer to in bloodstain pattern analysis?

  1. The two-dimensional region on a surface from which the lines drawn through stain long axes intersect Correct answer.
  2. The three-dimensional point in space where the blood originated
  3. The region of a stain with the highest concentration of blood
  4. The area where blood pooled on the floor

Explanation

The area of convergence is determined by drawing lines through the long axes of individual stains back to their intersection on the target surface. It is a two-dimensional construct that helps locate the region from which the blood traveled. It is distinct from the area of origin, which adds a third dimension.

Question 10Bloodstain Pattern

How is the area of origin of a bloodstain spatter pattern determined?

  1. By locating the nearest vertical surface
  2. By identifying the largest stain in the pattern
  3. By combining the area of convergence with the calculated angles of impact to project stains back in three dimensions Correct answer.
  4. By measuring the total volume of blood in the pattern

Explanation

The area of origin is established by using the area of convergence together with the impact angles of individual stains. Strings or software project the stains back along their trajectories to find the three-dimensional point of origin. This requires stains with reliable directional information.

Question 11Bloodstain Pattern

Which bloodstain feature indicates the direction of travel of a droplet that struck a surface at an oblique angle?

  1. The circular shape of the stain
  2. The pointed or tapered end of the stain Correct answer.
  3. The overall color of the stain
  4. The presence of a pool beneath the stain

Explanation

When a droplet strikes at an oblique angle, it produces an elongated stain with a tapered end that points in the direction of travel. The wider, rounded end faces the source. This directional feature is used to trace stains back toward the area of convergence.

Question 12Bloodstain Pattern

What is the significance of a 'satellite' or 'spine' feature on a bloodstain?

  1. It indicates that the stain was produced by transfer
  2. It indicates that the droplet struck with sufficient energy to produce secondary droplets around the parent stain Correct answer.
  3. It indicates that the stain is older than surrounding stains
  4. It indicates that the blood was diluted with water

Explanation

Satellite stains and spines form when a droplet impacts with enough energy that smaller secondary droplets break away and land around the main stain. Their presence reflects the dynamics of the impact. They are commonly seen in spatter patterns rather than in passive drips.

Question 13Bloodstain Pattern

A bloodstain pattern shows a fine mist of very small droplets with a wide distribution. Which interpretation is most consistent with this observation?

  1. A slow flow of blood under gravity produced the pattern
  2. A passive drip from a stationary wound produced the pattern
  3. A high-energy impact such as a gunshot produced the pattern Correct answer.
  4. A single transfer from a bloody object produced the pattern

Explanation

High-energy impacts, such as gunshots or powerful blunt-force strikes, produce fine mist-like spatter with very small droplets distributed over a wide area. The energy imparted to the blood determines the droplet size distribution. Passive and transfer mechanisms produce larger, more localized stains.

Question 14Bloodstain Pattern

What distinguishes a 'swipe' pattern from a 'wipe' pattern in bloodstain analysis?

  1. A swipe involves cast-off and a wipe involves expiration
  2. A swipe is the transfer of blood onto a surface by a moving bloody object, whereas a wipe is the alteration of an existing stain by a moving object Correct answer.
  3. A swipe is a three-dimensional pattern and a wipe is two-dimensional
  4. A swipe is produced by gravity and a wipe is produced by impact

Explanation

A swipe occurs when a blood-bearing object moves across a clean surface, depositing blood. A wipe occurs when a moving object passes through wet blood already on a surface, altering or removing it. The distinction concerns whether blood is added or redistributed.

Question 15Bloodstain Pattern

Which term describes the change in a bloodstain pattern caused by an object moving through wet blood after the pattern was deposited?

  1. Expiration
  2. Projection
  3. Convergence
  4. Alteration Correct answer.

Explanation

Alteration refers to any change to an existing bloodstain or pattern after deposition, such as wiping, smearing, or dilution. Recognizing alteration is important because it can obscure the original pattern. Convergence, projection, and expiration describe different concepts.

Question 16Bloodstain Pattern

A bloodstain appears lighter at the edges with a darker, well-defined rim. What does this feature most likely indicate?

  1. The stain was produced by a high-velocity impact
  2. The stain was formed by blood pooling over a long period
  3. The stain was created by a swipe transfer
  4. The stain was formed by a drop that spread and dried with a concentrated edge Correct answer.

Explanation

A drop that strikes a non-porous surface can spread and dry with a darker rim where blood concentrates at the edge as it evaporates. This is a characteristic drying feature of a single droplet stain. It is not diagnostic of impact velocity or transfer.

Question 17Bloodstain Pattern

What is the primary purpose of documenting bloodstain patterns with photographs and measurements at a scene?

  1. To establish the legal guilt of a suspect
  2. To identify the blood type of the donor
  3. To preserve the spatial relationships and appearance of patterns for later reconstruction and review Correct answer.
  4. To determine the exact age of the bloodstains

Explanation

Documentation preserves the size, shape, location, and orientation of bloodstain patterns so they can be analyzed and reconstructed after the scene is altered. Measurements and photographs allow analysts to revisit the geometry later. It does not by itself establish age, blood type, or guilt.

Question 18Bloodstain Pattern

A pattern of parallel linear bloodstains is found on a wall near a victim. Which pattern type is most consistent with this finding?

  1. Expirated blood from the airway
  2. Pooling on a horizontal surface
  3. Passive drip from a stationary source
  4. Cast-off from a swinging weapon Correct answer.

Explanation

Cast-off patterns commonly appear as a series of parallel linear stains on a vertical surface, reflecting successive swings and deceleration of a blood-bearing object. The linear, parallel arrangement is characteristic. Passive, expirated, and pooling patterns do not produce this appearance.

Question 19Bloodstain Pattern

Which factor most strongly influences the size of droplets produced in impact spatter?

  1. The angle of the receiving surface
  2. The color of the surface receiving the blood
  3. The age of the bloodstain
  4. The amount of energy imparted to the blood at impact Correct answer.

Explanation

The energy delivered to the blood at the moment of impact largely determines the size distribution of the resulting droplets. Higher energy generally produces smaller droplets. Surface color, surface angle, and stain age do not control droplet size in this way.

Question 20Bloodstain Pattern

In a bloodstain pattern, what is meant by the 'parent stain'?

  1. The oldest stain in the pattern
  2. The stain closest to the area of origin
  3. The primary stain from which secondary droplets were thrown off Correct answer.
  4. The largest pool at the scene

Explanation

The parent stain is the main stain produced by a droplet's impact, from which smaller satellite droplets may be thrown off. Its size and shape provide information about the impact. Pool size, proximity to origin, and age are unrelated to the definition.

Question 21Bloodstain Pattern

A stain measures 6 mm wide and 12 mm long. What is the approximate angle of impact?

  1. 90 degrees
  2. 30 degrees Correct answer.
  3. 45 degrees
  4. 60 degrees

Explanation

Using sine(angle) = width/length = 6/12 = 0.5, the inverse sine gives approximately 30 degrees. The stain is twice as long as it is wide, indicating a shallow impact angle. This calculation is a standard step in trajectory reconstruction.

Question 22Bloodstain Pattern

Which statement about the relationship between the angle of impact and stain elongation is correct?

  1. As the angle of impact decreases from 90 degrees, the stain becomes more circular
  2. As the angle of impact decreases from 90 degrees, the stain becomes more elongated Correct answer.
  3. Stain elongation is independent of the impact angle
  4. The angle of impact has no effect on stain shape

Explanation

At a 90-degree impact the stain is circular, and as the angle decreases the stain elongates along the direction of travel. The width-to-length ratio decreases accordingly. This relationship underpins the sine formula used in reconstruction.

Question 23Bloodstain Pattern

What is the primary limitation of using the area of origin calculation on a spatter pattern?

  1. It assumes stains selected are from a single event and that their trajectories are accurately measured Correct answer.
  2. It cannot be performed without laboratory equipment
  3. It requires the blood to be fresh
  4. It only works for passive drip patterns

Explanation

The area of origin calculation depends on selecting stains that belong to the same event and on accurate measurement of their dimensions and positions. Mixed or altered patterns can distort the projection. It does not require special laboratory equipment or fresh blood.

Question 24Bloodstain Pattern

Which bloodstain pattern would most likely be found on the clothing of an assailant who struck a victim repeatedly with a blunt object?

  1. Pooling on a horizontal surface
  2. An expirated pattern
  3. A drip trail
  4. Impact spatter Correct answer.

Explanation

Repeated blunt-force strikes generate impact spatter that can be deposited on the assailant's clothing and nearby surfaces. The energy of the strikes produces characteristic droplet patterns. Pooling, drip trails, and expirated patterns arise from different mechanisms.

Question 25Bloodstain Pattern

In bloodstain analysis, what does 'directionality' of a stain refer to?

  1. The chronological order in which stains were deposited
  2. The direction of blood flow within a pool
  3. The compass orientation of the surface
  4. The indication of the droplet's travel direction provided by the stain's shape Correct answer.

Explanation

Directionality refers to the information a stain carries about the direction the droplet was traveling when it struck. Elongated stains with tapered ends point in the direction of travel. This information is used to reconstruct trajectories.

Question 26Crime Scene

Under ISO/IEC 17025 and the IAI Code of Ethics, which practice is required of a crime scene investigator who documents and collects physical evidence?

  1. A summary report written only after the case is adjudicated
  2. Contemporaneous, verifiable records of every action taken with the evidence Correct answer.
  3. Verbal briefing of the prosecutor in place of written notes
  4. Destruction of rough notes once the formal report is typed

Explanation

Forensic practice requires contemporaneous documentation so that any later reviewer can reconstruct what was done, by whom, and when. Rough notes are retained and treated as discoverable evidence, not discarded after report writing. Verbal-only communication breaks the chain of verifiability.

Question 27Crime Scene

What is the primary purpose of establishing a chain of custody for an item of physical evidence?

  1. To confirm the item was analyzed by an accredited laboratory
  2. To prove the item was photographed before being packaged
  3. To record every transfer and storage condition from collection to disposition Correct answer.
  4. To certify that the item is relevant to the alleged offense

Explanation

Chain of custody is a chronological record of custody, control, transfer, and storage of evidence. It demonstrates that the item was not tampered with or substituted between seizure and courtroom use. Relevance and analytical accreditation are separate matters.

Question 28Crime Scene

A scene is a single-family residence where a burglary occurred through a rear window while the occupants were away. Which area is properly treated as the primary scene?

  1. The rear window and the rooms the intruder traversed Correct answer.
  2. The patrol vehicle used by the first responding officer
  3. The forensic laboratory where latent prints are developed
  4. The police property room where seized items are stored

Explanation

The primary scene is where the criminal act and its immediate physical consequences occurred, including the point of entry and the path taken inside. Vehicles, laboratories, and property rooms are secondary or ancillary locations that may hold evidence but are not the scene of the offense.

Question 29Crime Scene

Which statement best describes the role of the first responding officer at a crime scene?

  1. Develop latent prints on surfaces before they are disturbed
  2. Conduct interviews of all witnesses and record formal statements
  3. Secure the scene, render aid, and preserve conditions until investigators arrive Correct answer.
  4. Release the scene to the occupants once photographs are taken

Explanation

The first responder's priorities are officer and public safety, medical aid, scene security, and preservation of conditions. Detailed witness statements and evidence processing belong to investigators and specialists. Only the responsible investigator authorizes release of the scene.

Question 30Crime Scene

What is the correct procedure when a firearm is found at a crime scene and must be transported to the laboratory?

  1. Record its condition and position, unload it safely if trained, and package it securely with documentation Correct answer.
  2. Cock the weapon to confirm it is unloaded, then place it loose in an evidence bag
  3. Pick it up by the barrel, insert a pen in the muzzle, and carry it to the vehicle
  4. Clean the weapon of visible debris before packaging to prevent corrosion

Explanation

The firearm's condition and location must be documented before it is moved, and it should be made safe by a trained person and packaged to prevent movement and loss of trace evidence. Inserting objects in the muzzle or carrying by the barrel can destroy or transfer trace evidence and is unsafe. Cleaning evidence is never appropriate.

Question 31Crime Scene

Which packaging choice is most appropriate for a bloodstained cotton shirt collected from a scene?

  1. A sealed plastic bag while still damp
  2. A breathable paper bag or box, dried before sealing Correct answer.
  3. A glass jar with a metal lid
  4. A vacuum-sealed plastic pouch

Explanation

Biological evidence must be allowed to dry and then packaged in breathable paper to prevent moisture buildup that promotes degradation and microbial growth. Sealed plastic traps moisture and can degrade DNA. Glass and vacuum packaging are unsuitable for bulky fabric items.

Question 32Crime Scene

During a scene search, investigators decide to use a strip or lane search pattern. What characteristic defines this pattern?

  1. Parallel lanes traversed in one direction, then re-traversed at right angles Correct answer.
  2. Concentric circles moving inward toward a central point
  3. Zones assigned to individual searchers working independently
  4. A spiral expanding outward from the point of entry

Explanation

A strip or lane search moves searchers along parallel lines across the area, and the area is often searched again at right angles to improve coverage. Concentric and spiral patterns radiate from a central point, while zone searches divide the scene into assigned sectors.

Question 33Crime Scene

A latent footwear impression is found in a thin layer of dust on a tiled floor. Which approach best preserves it for comparison?

  1. Vacuum the floor and submit the vacuum filter
  2. Spray it with a clear lacquer to fix the dust in place
  3. Wipe the area with a damp cloth and submit the cloth
  4. Photograph it with a scale, then lift it with an electrostatic dust lifter or gelatin lifter Correct answer.

Explanation

Dust impressions are fragile and should be photographed with a scale before any lifting attempt. Electrostatic dust lifting or gelatin lifters recover the impression without destroying the detail. Lacquer sprays and wiping alter or destroy the impression.

Question 34Crime Scene

Which condition most strongly justifies treating a death scene as a homicide scene until proven otherwise?

  1. The scene contains prescription medication
  2. The body was found in a locked residence
  3. The body shows injuries inconsistent with the reported circumstances Correct answer.
  4. The decedent was elderly and lived alone

Explanation

Injuries or scene findings that do not fit the reported circumstances require investigators to proceed cautiously and treat the death as suspicious. Age, medication, and a locked residence are common features of natural deaths and do not by themselves indicate homicide.

Question 35Crime Scene

What is the principal advantage of using a total station or photogrammetry system at a large outdoor scene?

  1. It automatically determines the cause of the incident
  2. It records precise three-dimensional coordinates of evidence and scene features Correct answer.
  3. It replaces the requirement for a written scene log
  4. It eliminates the need for any photographs of the scene

Explanation

Total stations and photogrammetry capture accurate spatial coordinates that support reconstruction and mapping. They supplement, rather than replace, photography and documentation, and they cannot determine causation.

Question 36Crime Scene

Which action best preserves potential DNA evidence on a beverage can recovered from a table?

  1. Swab the entire exterior with a wet swab and discard the can
  2. Rinse it with water to remove food residue before packaging
  3. Handle it minimally by the edges, air-dry if wet, and package it in a paper container Correct answer.
  4. Seal it in a plastic bag while still wet

Explanation

Touch DNA is best preserved by minimal handling and by drying wet items before packaging in breathable material. Swabbing the whole exterior dilutes and mixes DNA, and sealing wet items in plastic promotes degradation. Rinsing removes the very material of interest.

Question 37Crime Scene

At a scene, a fragment of broken glass is found that may have come from a window broken during entry. Which documentation step is most important before collection?

  1. Estimate its monetary value for the property report
  2. Record its exact location and orientation relative to the window and other items Correct answer.
  3. Ask the homeowner whether the glass looks familiar
  4. Clean the fragment so its edges are clearly visible

Explanation

The evidentiary value of glass fragments depends heavily on their spatial relationship to the window and other items, which can support or refute a sequence of events. Cleaning or estimating value does not preserve that information.

Question 38Crime Scene

A scene contains a suspected accelerant pour pattern on a wooden floor. Which collection method is most appropriate?

  1. Collect a sample of the charred material and an adjacent comparison sample in separate airtight containers Correct answer.
  2. Wash the floor with solvent and submit the washings
  3. Collect only the most heavily burned material in a paper bag
  4. Collect a single sample and store it in an open container

Explanation

Fire debris analysis requires an airtight container to retain volatile compounds, and a comparison sample from an unaffected area is needed to distinguish background from accelerant. Paper bags allow volatile loss, and open storage permits evaporation.

Question 39Crime Scene

Which factor is most critical when deciding whether to use alternative light sources on a scene?

  1. Whether the investigator has a written warrant
  2. Whether the occupants are present during the examination
  3. Whether the room has adequate overhead lighting
  4. Whether the surface and suspected evidence will fluoresce or absorb at the selected wavelength Correct answer.

Explanation

Alternative light sources reveal evidence only when the material of interest responds differently from the substrate at the chosen wavelength. Ambient lighting, legal authority, and occupancy are separate considerations and do not determine the technical suitability of the technique.

Question 40Crime Scene

What is the purpose of including a scale in forensic photographs of an item of evidence?

  1. To indicate the photographer's identity
  2. To satisfy a requirement that every photograph contain a person
  3. To replace the need for written measurement records
  4. To allow accurate size determination and demonstrate that the item was not altered Correct answer.

Explanation

A scale provides a reference for size and supports the argument that the item was photographed as found. It does not replace written measurements, identify the photographer, or require a person in the frame.

Question 41Crime Scene

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

  1. Secure and assess, document, search and collect, then package and transfer with documentation Correct answer.
  2. Collect evidence first, then secure the scene and photograph it
  3. Interview witnesses before securing the scene
  4. Photograph the scene after all evidence has been removed

Explanation

The generally accepted sequence moves from securing and assessing the scene, through documentation, to systematic search and collection, and finally packaging and transfer with complete records. Collecting before documenting loses context, and removing evidence before photography destroys the record.

Question 42Crime Scene

An investigator finds a cell phone on a table near a victim. Which action is most appropriate at the scene?

  1. Place it in a plastic bag without documentation
  2. Turn it on and check recent calls to identify suspects
  3. Remove the battery immediately regardless of model
  4. Document its position, avoid operating it, and preserve power state before packaging Correct answer.

Explanation

Digital devices should be documented in place and handled so that their state is preserved; operating the device can alter data and network records. Power state preservation depends on the device and circumstances, and the item must be documented before packaging.

Question 43Crime Scene

Which statement about control or comparison samples at a crime scene is accurate?

  1. They are stored without chain of custody because they are not evidence
  2. They provide known reference material needed to interpret the evidentiary sample Correct answer.
  3. They are collected only when the suspect confesses
  4. They are optional and rarely useful in forensic analysis

Explanation

Control samples, such as known fibers, glass, or reference DNA, allow the analyst to distinguish evidentiary material from background and to make meaningful comparisons. They are evidence and require the same documentation and custody controls.

Question 44Crime Scene

A scene is contaminated when an investigator walks through a pool of blood before it is documented. Which principle does this most directly violate?

  1. The duty to clean the scene before departure
  2. The rule against collecting biological evidence
  3. The requirement to interview the suspect first
  4. Preservation of the scene in its original condition Correct answer.

Explanation

Investigators must preserve the scene as found so that evidence positions and conditions remain meaningful. Walking through blood alters the pattern and can transfer material, compromising reconstruction. Interviewing suspects and cleaning the scene are unrelated or improper actions.

Question 45Crime Scene

Which documentation method best supports later reconstruction of a bloodstain pattern at a scene?

  1. A sketch made without measurements
  2. A single wide-angle photograph taken from the doorway
  3. A verbal description recorded from memory days later
  4. Overhead and oblique photographs with scales, plus measurements of stain positions Correct answer.

Explanation

Bloodstain pattern reconstruction depends on accurate geometry, so photographs from multiple angles with scales and measured positions are essential. A single doorway photo, delayed memory, or an unmeasured sketch cannot support reliable analysis.

Question 46Crime Scene

Which of the following is the most appropriate way to document the condition of a door that shows tool marks around the latch?

  1. Photograph the marks with a scale and cast or mold them if detail permits Correct answer.
  2. Remove the entire door without photographs
  3. Paint over the marks to prevent further damage
  4. Open and close the door repeatedly to test the lock

Explanation

Tool mark evidence must be photographed with a scale and, where feasible, cast or molded to preserve fine detail for comparison. Repeated manipulation can alter the marks, and removing the door without documentation loses context.

Question 47Crime Scene

Which statement about scene sketches is correct?

  1. They should be drawn to artistic scale without a legend
  2. They may omit measurements if photographs exist
  3. They should include measurements and a legend so positions can be verified Correct answer.
  4. They are created after the case closes

Explanation

A scene sketch is a measured diagram that records the relative positions of evidence and fixed reference points, with a legend explaining symbols. Photographs do not replace measurements, and sketches are prepared during or shortly after processing.

Question 48Crime Scene

An investigator must collect a dried paint chip from a wall for comparison with paint transferred to a tool. Which approach is most appropriate?

  1. Collect only the questioned chip and submit it alone
  2. Submit a photograph of the wall in place of samples
  3. Scrape the entire wall area into one container
  4. Collect the questioned chip and a known sample from the same wall area, each separately packaged and labeled Correct answer.

Explanation

Paint comparison requires both the questioned fragment and a known sample from the source, each packaged and labeled separately to avoid cross-contamination. Submitting only the questioned fragment or mixing samples prevents meaningful comparison, and a photograph cannot substitute for physical analysis.

Question 49Crime Scene

A scene has been processed and the investigator must decide when to release it. Which consideration is most important?

  1. Whether the media have finished filming the scene
  2. Whether the case has already been solved
  3. Whether the occupants are impatient to return
  4. Whether all necessary documentation and evidence collection have been completed and verified Correct answer.

Explanation

Release of a scene should follow verification that documentation, search, and collection are complete and that nothing further is needed. Media schedules, occupant impatience, and premature conclusions about the case are not valid bases for release.

Question 50Crime Scene

An investigator must decide whether to treat a fire scene as accidental or incendiary. Which approach is most defensible?

  1. Conclude incendiary cause based on the darkest burn area
  2. Rely on the smell of accelerant as the sole basis for the conclusion
  3. Assume accidental cause unless a witness reports a suspect
  4. Systematically document burn patterns, collect debris and comparison samples, and rely on laboratory analysis rather than appearance alone Correct answer.

Explanation

Fire cause determination requires systematic documentation, collection of debris and comparison samples, and laboratory confirmation of ignitable liquids. Burn appearance alone, witness reports, and odor are insufficient and can be misleading.