Preserving Evidence at a Crime Scene Practice Questions

25 multiple-choice questions on Preserving evidence at a crime scene for paramedic and EMT students, from Chapter 53 (Crime Scene Awareness). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. Locard's exchange principle explains why EMS can affect a crime scene. It states that:

   1. A. Every contact leaves a trace behind
   2. B. Evidence must be bagged before it is valid
   3. C. Responders rarely alter a scene
   4. D. Trace evidence is lost within an hour
   Show answer

   Answer: A. Every contact leaves a trace behind

   Whenever two things touch, material is exchanged: you can leave hair, fibers, and footprints and carry away trace evidence on your gloves, shoes, and equipment, which is why you limit contact to what care requires. Packaging affects chain of custody, not the exchange principle. Responders alter scenes often, which is the point of the principle. Trace evidence can persist for long periods if undisturbed.

2. Hair, fibers, soil, and glass fragments found on a victim's clothing are examples of:

   1. A. Testimonial evidence
   2. B. Trace evidence
   3. C. Documentary evidence
   4. D. Digital evidence
   Show answer

   Answer: B. Trace evidence

   Trace evidence is small physical material transferred between people, objects, and places, and it is easily lost when clothing is shaken, moved, or handled more than needed. Testimonial evidence is what a witness says. Documentary evidence is written or recorded material such as reports. Digital evidence comes from phones, computers, and cameras.

3. You can reach a stabbing victim in a backyard by the front walkway, where you see drops of blood, or by a side gate with no visible marks. You should:

   1. A. Use the walkway, since it is the shortest way
   2. B. Use both, so the crew can get there faster
   3. C. Follow the blood drops to find any suspects
   4. D. Use the side gate and tell police your route
   Show answer

   Answer: D. Use the side gate and tell police your route

   When you have a choice, take the route least likely to hold evidence, such as blood trails or footprints, and tell police which way you came and went. Following blood drops can destroy the trail investigators need.

4. To work on a cardiac arrest victim, you must push a coffee table aside at a homicide scene. You should:

   1. A. Put it back after the call to fix the scene
   2. B. Avoid moving it and do CPR around it
   3. C. Note where it was and tell the police
   4. D. Leave it out of the report to save time
   Show answer

   Answer: C. Note where it was and tell the police

   Patient care comes first, so move what you must, but note what you moved and its original position and tell police. Putting it back creates a false picture, and working around it can compromise CPR.

5. A woman has been shot in her kitchen. While you wait for the helicopter, your partner wants to wash his bloody gloves in her sink. You should:

   1. A. Let him, since gloves must be clean for care
   2. B. Have him use the bathroom sink upstairs
   3. C. Let him, if he wipes the sink afterward
   4. D. Tell him not to use anything in the scene
   Show answer

   Answer: D. Tell him not to use anything in the scene

   Using a scene's sink, toilet, phone, or towels can destroy or contaminate evidence such as blood or prints. Change gloves from your own supplies instead.

6. At a homicide scene, police tape paper bags over the dead victim's hands. This is done mainly to:

   1. A. Preserve evidence on the hands
   2. B. Keep the hands warm for later fingerprinting
   3. C. Slow the onset of rigor mortis in the fingers
   4. D. Protect the crew from contact with the blood
   Show answer

   Answer: A. Preserve evidence on the hands

   Paper bags protect gunshot residue, an attacker's skin or blood under the nails, and fibers until the medical examiner collects them; paper is used because it lets moisture escape. This is also why EMS avoids wiping or handling a victim's hands unless care requires it. Warmth does not matter for fingerprinting. Bags do not change the timing of rigor mortis. Gloves, not bags on the body, protect the crew.

7. You notice several shell casings on the floor around a shooting victim. You should:

   1. A. Pick them up so no one slips
   2. B. Avoid stepping on or moving them
   3. C. Count them and put them in your pocket
   4. D. Push them aside to clear a work area
   Show answer

   Answer: B. Avoid stepping on or moving them

   Casings show where shots were fired and can link a weapon to the crime. Work around them, and if one is disturbed, tell police; collecting them is the investigators' job.

8. A shooting victim's shirt is soaked with blood when you remove it. Before handing it to police, you should not:

   1. A. Keep it apart from the other clothing
   2. B. Place it in a paper evidence bag
   3. C. Shake it out or fold it while wet
   4. D. Tell the officer where it came from
   Show answer

   Answer: C. Shake it out or fold it while wet

   Shaking clothing scatters trace evidence such as fibers and gunshot residue, and folding wet bloodstains can smear patterns. Lay it in a paper bag as is, separately from other items.

9. Bloody clothing is placed in paper rather than plastic bags mainly because plastic:

   1. A. Lets the wet blood soak through and stain other items
   2. B. Releases chemicals that alter DNA
   3. C. Lets fingerprints rub off onto the plastic
   4. D. Traps moisture that lets the evidence degrade
   Show answer

   Answer: D. Traps moisture that lets the evidence degrade

   Plastic holds in moisture, which lets bacteria and mold break down blood and DNA evidence. Paper breathes, so the item can dry. Plastic is less likely than paper to let blood soak through, and it does not release chemicals that alter DNA; the problem is the moisture it traps.

10. A gap in the chain of custody for a piece of evidence can lead to:

    1. A. The evidence being ruled inadmissible
    2. B. The whole case being dismissed at once
    3. C. The evidence needing to be retested
    4. D. A mistrial declared on the spot
    Show answer

    Answer: A. The evidence being ruled inadmissible

    If the record of who handled evidence and when has a gap, the defense can argue it was tampered with, and a court may exclude it. That is why every handoff is documented. A gap does not by itself end the whole case or cause a mistrial, and retesting cannot repair an unknown handling history.

11. At the hospital, you find a bullet on the stretcher after moving off a gunshot victim. You should:

    1. A. Mark it with your initials and keep it safe
    2. B. Give it to police and document the handoff
    3. C. Put it in the patient's belongings bag
    4. D. Throw it in the sharps container safely
    Show answer

    Answer: B. Give it to police and document the handoff

    A bullet is key physical evidence. Handle it minimally, give it to law enforcement, and document when, where, and to whom; marking it or mixing it with belongings breaks the chain of custody.

12. At a home where a man has been beaten, which observation is most useful to document for investigators?

    1. A. Whether doors were locked and lights were on
    2. B. The brand of the television in the living room
    3. C. The number of houseplants in the front room
    4. D. The patient's favorite sports team on the wall
    Show answer

    Answer: A. Whether doors were locked and lights were on

    Scene conditions on arrival, such as locked or forced doors, lights, odors, and who was present, may be key to the investigation and can change once others arrive. Decor details rarely matter.

13. Your crew walked through a pool of blood to reach a stab victim. Afterward, you should:

    1. A. Wash your boots at the scene before leaving
    2. B. Leave it out of the report to avoid blame
    3. C. Tell police so they can tell your prints apart
    4. D. Wipe up the blood you tracked across the floor
    Show answer

    Answer: C. Tell police so they can tell your prints apart

    Bloody shoe prints can be mistaken for the suspect's. Tell investigators, who may photograph your soles to rule out your prints; cleaning the scene or your boots there destroys evidence.

14. Which statement about gloves and fingerprints at a crime scene is correct?

    1. A. Gloves protect existing prints from smearing
    2. B. Gloves can smear prints that are already there
    3. C. Fingerprints fade within a few minutes
    4. D. Gloves leave prints that are easy to read
    Show answer

    Answer: B. Gloves can smear prints that are already there

    Gloves keep you from leaving your own prints but can still smudge or wipe away existing prints. Touch only the surfaces you must.

15. When you leave a homicide scene after a failed resuscitation, the medical debris your crew generated should be:

    1. A. Left mixed in with scene items without comment
    2. B. Thrown in the trash cans found in the residence
    3. C. Kept if bloody, with the rest thrown away
    4. D. Handled per police direction, and identified as yours
    Show answer

    Answer: D. Handled per police direction, and identified as yours

    Wrappers, gloves, and other EMS debris can confuse investigators. Follow police direction on whether to remove or leave it, and identify what came from your crew; never use the scene's trash cans.

16. Police ask you to park your ambulance on the street instead of the driveway at a hit-and-run scene. The most likely reason is to:

    1. A. Keep the drive clear for a tow truck later
    2. B. Protect tire marks and debris in the driveway
    3. C. Give the fire engine room to park in the drive
    4. D. Make sure the unit is clear of the hydrant
    Show answer

    Answer: B. Protect tire marks and debris in the driveway

    Tire marks, skid patterns, paint chips, and broken glass are important evidence in hit-and-run and crash investigations. Parking and walking away from them protects what investigators need. A tow truck or fire engine can be placed elsewhere, but marks that are driven over cannot be recovered.

17. A man was shot outside a store and a handgun lies within his reach. Police have not arrived, and you must move the gun to treat him safely. You should:

    1. A. Unload it and place the bullets in your pocket
    2. B. Hand it to a bystander to hold until police arrive
    3. C. Move it out of reach as is, and note where it was
    4. D. Wipe it clean before setting it in the ambulance
    Show answer

    Answer: C. Move it out of reach as is, and note where it was

    Scene safety comes first, but the weapon is also evidence. If you must move it, handle it by the edges of the grip with gloved hands, keep the muzzle pointed in a safe direction, do not unload it, place it out of reach and in view, and tell police exactly where it was and what you did.

18. A gunshot victim was lying on your stretcher sheet during transport. After the call, the sheet should be:

    1. A. Washed with the other linens at the hospital
    2. B. Thrown away in the regular trash at the ED
    3. C. Folded and kept in the ambulance for later
    4. D. Given to police in a paper bag, if requested
    Show answer

    Answer: D. Given to police in a paper bag, if requested

    Linens may hold trace evidence such as fibers, glass, or bullet fragments. If police want them, they should be bagged in paper and handed over with chain-of-custody documentation.

19. Arriving at a snowy yard for an assault victim, you see a line of fresh footprints leading from the body toward the street. You should:

    1. A. Walk around them and point them out to police
    2. B. Walk in them so you leave no new prints
    3. C. Cover them with a blanket from your unit
    4. D. Follow them to see where the suspect went
    Show answer

    Answer: A. Walk around them and point them out to police

    Footprints can show a suspect's path and shoe type. Avoid stepping on or near them and tell police; walking in them destroys their detail, and following them is not your role.

20. At a crime scene, which surfaces should you avoid touching unless care requires it?

    1. A. Your own monitor screen and its cables
    2. B. The inside of your gloves while changing
    3. C. The stretcher rails as you lift the patient
    4. D. Door handles, frames, and light switches
    Show answer

    Answer: D. Door handles, frames, and light switches

    Door handles, frames, light switches, and similar surfaces are where a suspect is likely to leave fingerprints. Touching them, even with gloves, can smear or destroy prints.

21. You arrive to find a man in a driveway with a gunshot wound and police not yet on scene. While you treat him, a bystander starts picking up items near him. You should:

    1. A. Let him gather them to keep them from being lost
    2. B. Ask the bystander to stop and tell police
    3. C. Ask him to put them in your ambulance for police
    4. D. Ignore him; evidence is not your concern
    Show answer

    Answer: B. Ask the bystander to stop and tell police

    Bystanders can disturb or remove evidence. Ask them not to touch anything and report what was moved; you do not collect evidence yourself, but you should help protect it.

22. A woman says she scratched her attacker's face during an assault. Her hands are bloody, but she has no wounds on them. You should:

    1. A. Wash her hands so she feels more comfortable
    2. B. Clean under her nails with an alcohol swab
    3. C. Leave her hands as they are and tell the ED
    4. D. Have her wipe her hands on a towel at home
    Show answer

    Answer: C. Leave her hands as they are and tell the ED

    Skin and blood under the fingernails may contain the attacker's DNA. Unless care requires cleaning, leave the hands alone and tell the receiving staff so they can collect it.

23. Police have taped off the yard around a shooting victim who has already been taken to the hospital. You left a bag inside the tape. You should:

    1. A. Ask an officer before going back inside the tape
    2. B. Duck under the tape and grab it quickly yourself
    3. C. Leave the bag behind and never mention it
    4. D. Send a bystander in to pick it up for you
    Show answer

    Answer: A. Ask an officer before going back inside the tape

    Once the patient is gone, the reason for EMS to be inside the perimeter is gone too. Ask police, who may escort you or retrieve the bag and note the entry; every extra trip in alters the scene.

24. You treated a woman at a home and then learn she was assaulted there. Your report should include:

    1. A. Your own theory about how the assault happened
    2. B. The name of the person you think did it
    3. C. Her vital signs and care, without scene details
    4. D. What you moved and where it was first found
    Show answer

    Answer: D. What you moved and where it was first found

    Documenting anything you moved, cut, or altered lets investigators reconstruct the original scene. Guessing at how the crime occurred or who did it is outside your role and can harm the case. Limiting the report to vital signs and care leaves out scene changes that investigators need.

25. A rape suspect is your patient after a fall during his arrest. His clothing may hold the victim's trace evidence. You should:

    1. A. Keep his clothing apart from any other items
    2. B. Bag it with the victim's clothes for the police
    3. C. Let him change into clothes from his car
    4. D. Wash any blood from his hands for comfort
    Show answer

    Answer: A. Keep his clothing apart from any other items

    Clothing from a suspect and a victim must never be packaged or transported together, since cross-contamination can ruin the evidence. Keep each person's items separate and give them to police.