Emergency Medical Services in the Crime Scene

Emergency medical responders are ill prepared for forensic considerations at the scene of a crime. (Photo/Amos P. Cameron)

EMS professionals are expected to respond to incidents that are often the results of criminal acts and then find themselves rendering emergency patient care at crime scenes. Disturbance of the crime scene and destruction of evidence may result in a serious injustice with a criminal perpetrator not being identified or let go scot-free. By changing the general approach and ideology of how EMS providers approach all scenes, medical responders can greatly reduce crime scene contamination and potential destruction of evidence. Common ground can combine exceptional prehospital medical care practices with good crime scene management and investigative practices.



Most criminal law is embodied in state criminal codes or penal codes, despite an increasing number of federal criminal statutes in Title 18 of the U.S. Code. Over 95% of crimes are prosecuted in state and local courts.1 Furthermore, although federal crimes have become extensive and include the Violent Crime Control and Law Enforcement Act of 1994; nonetheless, they are less likely to apply to the crime scenes involving violence.

The FBI gathers information on crimes throughout the country for its Uniform Crime Reporting (UCR) service. This data is gathered from participating law enforcement agencies to produce national crime estimates. 

The UCR does not report all crimes, but reports the following major crimes for the year 2018:2

The scenes of crimes involving violence occurred in the following locations and had a victim sex and race distribution as follows in 2018:3

The ages of the victims were as follows:

The weapons used were reported as:

It is important for EMS and other emergency responders to bear in mind that crime is not only limited to murder, rape and assaults. The practice of emergency responders only treating a crime scene as a crime scene, when it involves violence, needs transformation. A narrow view of a criminal act has a propensity to lead to carelessness in attempting to preserve the integrity of a crime scene, especially when the first step in recognizing that a crime has taken place was missed. Thus, emergency responders need to become less dismissive of crimes not classified as a heinous personal crime.

Crime Scenes

A crime scene is defined as any physical location that may contain or provide potential evidence to investigators–not just the incident scene.4 Although, a crime may occur at one location, the crime scene can extend to a multitude of different locations. Transfer of evidence is a key concept of forensic science. This issue has great implications for emergency responders who respond to requests for help even if they have no knowledge that a crime had taken place. EMS personnel respond to various locations ranging anywhere from nursing homes to international terrorism incidents. Often, the requests are for a victim at a location distant from where the crime occurred, yet at a location that contains evidence. Emergency responders should consider all locations to be scenes at which evidence may potentially be found.


Responders should be aware that evidence is ubiquitous and wide-ranging. Evidence can be anything from huge items down to minute traces of blood or body fluids.5 It can include biological samples, fibers, photographs, videos, drawings, plans and documentary evidence such as receipts or bank statements. Locard’s exchange principle holds that every contact leaves a trace.3 This fact is the basis of forensic investigation, in which investigators identify those traces through analysis to explain what has happened. Responders should be focused on care of the patient and should presume that the site contains evidence avoiding disturbance of the site more than necessary. 

Near ubiquitous video surveillance yields digital evidence that is often very helpful to investigations and prosecutions. Nonetheless, such digital evidence has yet to replace the need for physical forensic evidence. However, the capture of images of the crime by cameras should match the physical evidence recovered. 

First Responder Priorities

In responding to a scene, law enforcement responders must determine the need for medical assistance, conduct a scene walk through, take steps to preserve and protect the area, secure and isolate the crime scene using crime scene tape or barricades, exclude all unauthorized personnel from the scene, and determine the lead investigator.6 Emergency medical responders should respect the efforts and needs of the law enforcement officials. When the medical responder is first on scene, then he or she must, to the extent possible, assume the responsibility for maintaining scene integrity until this responsibility is transferred to responding law enforcement personnel.

Providing Medical Care

Upon arrival on any scene, emergency medical responders are taught to: assess the scene for safety hazards and ensure that the scene is safe to respond and enter, take necessary precautions at donning all appropriate protective equipment for body substance isolation (i.e., gloves, gown, mask), performing a scene size up, requesting any additional resources as needed (i.e., rescue, fire, police, hazmat), and determining the number of patients at the scene.

EMS should view every scene as a potential crime scene when responding and remain diligent in maintaining this mindset. EMS response procedures can be combined with law enforcement response procedures thus maximizing the likelihood of preserving scene integrity should the scene be determined to be a crime scene. With due diligence, measures can be taken to assist law enforcement at preserving a crime scene without jeopardizing patient care.

As an emergency medical provider, detailed documentation of the scene and details of providers movements about the scene during life threatening emergencies can seem like a burden and hindrance, but it often proves crucial in later investigations and in court. The observations of the medics as they arrive are often the first professional observations of the scene. Furthermore, the expertise and neutral perspective of medical personal provides an important rationale for the importance of their notes. The wearing of body cameras may be useful in documenting that an emergency medical provider did or did not disturb an area of the scene; such recordings can be entered into the patient record and later obtained by investigators via subpoena. 

It is helpful for medical personnel to understand what the responsibilities and challenges of the other responders are, such as: patrol officers, detectives, and crime scene investigators, who must meticulously inspect, document, and recover evidence from the crime scenes. Understanding evidence collection procedures and scientific laboratory analysis of that evidence can provide a greater appreciation of the actions taken by initial responders on scene and the potential implications that may have on the prosecutorial aspects of the case.

Crime scene contamination is detrimental to any case. It is imperative that the movement of personnel at a crime scene is limited and the number of persons allowed into the crime scene is restricted to necessary personnel only. This practice of access restriction is critical to maintain integrity of the scene and minimizes potential contamination. People wandering through the area can render physical evidence useless. It is not implausible that someone inside the scene accidentally steps on a cartridge case involved in a shooting and carries it out in the lug of their boots. Every person present at the scene has the potential to destroy valuable evidence.5 This restriction includes supervisors down to unnecessary medics. 

Evidence Collection

At a crime scene, investigators are challenged with determining the truth of what occurred. While they consider means, motive and opportunity, they are also there to interpret the physical evidence. Taking a holistic approach by examining the physical evidence and witness accounts helps determine what occurred. The approach typically follows the scientific method by developing a hypothesis and either supporting or rejecting it.

Crime scene investigators have many responsibilities, which can often be challenging. While they work closely with other responders, they are responsible for the proper documentation and interpretation of the scene. Some of their responsibilities at a crime scene include photography, evidence collection, bloodstain pattern analysis, trajectory analysis and diagramming the scene. Presumptive analysis will be conducted on suspected blood or drugs, but a complete analysis of evidence will be conducted in a forensic laboratory.

Upon completion of documenting and interpreting the scene, the crime scene investigator will collect all the physical evidence. While collecting the evidence, the investigator has several things to consider; the type of evidence container, proper collection techniques and contamination. Evidence containers can range from a paper bindle and paper sacks to large boxes or wrapping large items in butcher paper. The investigator must consider whether the item can go into a plastic “non-breathable” container or if the evidence is in a gaseous state and needs to be sealed in a can. Collection techniques can range from simply picking the item up with gloved hands to using sterile swabs and tweezers. None of the evidence can be cross contaminated with other evidence, especially biological evidence that will be analyzed. Once the evidence is collected, it must be identified and properly packaged.

To maintain the integrity of the evidence, the chain of custody is documented for each item, whether by the crime scene technician or EMS responder. This written document lists each person who has been responsible for the evidence. Multiple individuals may each be responsible for collection and documentation or a single person can be tasked to handle all the evidence.

Investigators completing all of this can be a daunting task. Of course, providing emergency medical aid should be of the utmost importance, but care should be taken to avoid removing, destroying, adding or cross-contaminating evidence on the scene. Seemingly small details can cause confusion and difficulty for investigators in identifying what is evidence and what is not evidence. First responders can inadvertently leave fingerprints, footprints and DNA evidence behind that investigators now must provide an explanation for being at the scene.

Some examples of things investigators will consider that may not be immediately obvious to emergency responders are: blood and biological evidence, weapons, footprints, and broken glass or signs of a struggle. Investigators will look for evidence in and on; ceilings, floors and rugs, receipts, bank statements, travel tickets and computers.

As an emergency responder, it is imperative that these evidence collection and investigative techniques be in the forefront of your mind when responding to victims of crime. Keeping contamination of evidence to a minimum is of critical importance especially when violent personal crimes have taken place.

Laboratory Analysis

Laboratory analysis of evidence collected at the scene can encompass a variety of techniques and methods that are well beyond the scope of the explanation of this article. Screening tests might be performed in the field, but definitive analysis is performed in the laboratory. Laboratory analysis might include drug analysis, toxicology, DNA testing, or fingerprint comparisons, among others.

Particularly, DNA evidence has advanced mightily in recent years. DNA, otherwise known as deoxyribonucleic acid, is found in virtually every cell in the human body and contains the genetic makeup of an individual. Except between identical twins, the DNA will differ in its sequence from all other human beings–it is this uniqueness that makes DNA of interest to investigators in helping to solve crimes. Today’s DNA technology involve a process called PCR or polymerase chain reaction that makes copies of the target DNA code, thus making it very sensitive. Routine “STR analysis” is very sensitive and powerful, but special DNA testing (“mitochondrial DNA sequencing” and “SNP analysis”) can be even more sensitive and applicable to degraded samples. In the 1996 case of Tennessee v. Ware, DNA analysis of a single hair, without the root of the hair, found in a victim’s throat, provided critical evidence in conviction of a capital murder case.7 DNA is that important!

Crime scene investigators will look for trace evidence, and particularly fingerprints and biologic specimens, including sweat, saliva, semen, urine, feces, blood, and skin, found on weapons, clothing, glasses, cigarette butts, bedding and other surfaces. Fingerprints and DNA profiles can identify the perpetrator. Searches will be conducted against local and national databases. Emergency medical responders should recognize that they could easily contaminate a scene with their own fingerprints and DNA. Investigators may want to obtain the fingerprints and DNA of responders, including emergency medical personnel, for this reason. 

A few things we can do to assist in avoiding contaminating evidence that may contain DNA are: always wear gloves and change them often, avoid touching or handling items that you believe may contain DNA evidence unless absolutely necessary, avoid talking, sneezing, and coughing around potential evidence. Never put biological evidence into plastic bags, doing so will cause moisture to collect and could degrade DNA.8


It comes as no surprise that emergency medical responders are ill prepared for forensic considerations of the scene as little time is devoted to this issue in their education and training. The American Academy of Orthopedic Surgeons AAOS Emergency Care in the Streets only dedicates a few paragraphs of text in the last chapter to this topic for paramedics. Given the importance of prosecuting offenders, we believe that it is important that emergency medical personnel be taught the need to preserve evidence at scenes and to take care to avoid unnecessary destruction and contamination of crimes scenes. Emergency medical responders need only be aware of forensic evidentiary considerations and have an attitude of respect for the scene. Specific steps to be taken, include: 

  1. Maintain a high index of suspicion and treat every scene as if it is a potential crime scene until proven otherwise.
  2. Recognize that evidence can be anything from huge items such as furniture to invisible trace evidence.
  3. Be cognizant of the impact of your actions on the scene.
  4. Develop a consistent, thorough and objective method of documentation that includes initial observations and what you and your crew did or moved on the scene.
  5. Follow direction and guidance of law enforcement on scene.
  6. If something must be moved to provide patient care, notify the investigator or law enforcement officer, to explain why the item is not in its original position.

The bottom line is that emergency medical providers should remain cognizant and vigilant of the possibility of forensic evidence. You should ask yourself questions like; if I move this how is that going to impact trajectory analysis or bloodstain analysis? If I track in a substance on my shoes from a prior location, how much valuable time is going to be wasted attempting to identify the gypsum that is still on my boots from the call at the drywall plant? These are things we need to be aware of as professionals when we enter these scenes.

By following these few simple steps, we can combine good prehospital medical care practices with good crime scene management and investigative practices. This will allow for those victims that can survive to receive good medical care and for the unfortunate realities of those who do not live, a successful prosecution in the courtroom.


  1. Sourcebook of Criminal Justice Statistics, University of New York at Albany, 2013 [Compare table 4.7 to table 4.33]. Retrieved 2020-17-September from: https://www.albany.edu/sourcebook/tost_4.html#4_f .
  2. DOJ FBI (n.d) 2018 Crime in the United States. Retrieved 2020-08-August from ucrfbi.gov: https://ucr.fbi.gov/crime-in-the-u.s/2018/crime-in-the-u.s.-2018/topic-pages/tables/table-2 .
  3. FBI Crime Data Explorer (n.d) 2008-2018 Crime Data Collection. Retrieved 2020-16-August from crime-data-explorer.fr.cloud.gov: https://crime-data-explorer.fr.cloud.gov/explorer/national/united-states/crime.
  4. UNODC. (2015). Online toolkit to Combat Trafficking in Persons. Retrieved 2020-13-August from Chapter 5 Law enforcement and prosecution: http://www.unodc.org/documents/human-trafficking/Toolkit-files/08-58296_tool_5-9.pdf.
  5. Forensics Talk. (2006-01-October). Crime Scene Procedures. Retrieved 2020-16-August from A forensic Nurse’s Weblog: https://harfordmedlegal.typepad.com/forensics_talk/2006/10/crime_scene_pro.html.
  6. UNODC. (2014). United Nations Office on Drugs and Crime Regional Office for Central Asia. Retrieved 2020-12-August from http://www.unodc.org/documents/centralasia/HTSM/SOP-Manual-UNODC_final_ENG.pdf.
  7. National Institute of Justice National Commission on the Future of DNA Evidence; (n.d) What every law enforcement officer should know about DNA Evidence. Retrieved August 14, 2020, from https://www.ncjrs.gov/pdffiles1/nij/bc000614.pdf.
  8. National Crimal Justice Reference Service. (2000, Summer). A DNA Evidence Primer. Retrieved August 19, 2020, from mafiadoc: https://mafiadoc.com/a-dna-evidence-primer_59ba16411723dddcc6db07f6.html.

Additional Resources

  • Dressler J, Understanding Criminal Law, 8th ed, Carolina Academic Press, Durham, NC, 2018.
  • Forsyth A, Common Law and Natural Law in America: From the Puritans to the Legal Realists, Cambridge University Press, Cambridge, UK, 2019
  • Gardner TJ, Anderson TM, Criminal Evidence: Principles and Cases, 9th ed, Cengage Learning, Boston, MS, 2016.
  • Mozayani A, Parish-Fisher C, Forensic Evidence Management: From the Crime Scene to the Courtroom, CRC Press, Boca Raton, FL, 2017.
  • Titus Reid S, Criminal Law: The Essentials, 3rd ed, Oxford Univ Press, Oxford, 2016.
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