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Investigative Tools and Equipment for Crime Scenes

Paper Type: Free Essay Subject: Criminology
Wordcount: 3787 words Published: 15th Aug 2018

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Homicides are punishable criminal acts that involve the killing of an individual by another person. Homicide cases can be either intentional or unintentional. Voluntary homicides are premeditated with the intent to kill such as murders, whilst unintentional homicides occur by mistake or negligence as in cases of fatal traffic accidents. However, these are tackled using the same investigative approach which comprises in using the correct apparatus and techniques to collect evidence from the crime scene, in filing of reports, in conducting searches, in interviewing witnesses and in interrogating suspects in order to arrest, prosecute and punish the offender.

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Investigative tools and equipment

To help the investigator in collecting all available evidence, a list of apparatus that is necessary to keep all proof intact and clean are brought on the crime scene. Universal Precautions such as a disinfectant and disposable gloves, jumpsuits, hair covers, shoe covers, purification masks, and face shields are important to help the investigator in safely touching the environment without tampering evidence and leaving fingerprints. An investigative notebook and stationary such as pens, markers, and pencils are also needed for writing down scene notes. Time reading is very important during the collecting of data such as time of arrival so a wristwatch would be ideal. Official identification of the investigator is also necessary since not everyone is allowed within a crime scene enclosed by crime scene tapes and barrier sheeting (Reno, Marcus, Robinson, Brennan, & Travis, 1999).

Body bags are brought to the scene to remove the body of the deceased safely from site and ID tags along with evidence seals are attached before removal from site. Cameras are needed to provide visual evidence for later study and measurement instruments such as tape and rulers are needed to record specific lengths or distances. Special containers such as specimen containers are needed to carry and preserve blood, general fluids, and other evidence items to the laboratory. Medical equipment kits are useful for gathering evidence that are complicated to obtain such as scissors to cut clothing samples or cotton-tipped swabs for picking out fluid samples. A trace evidence kit, a first aid kit, a latent print kit, a gunshot residue kit, a blood test kit, a thermometer, local maps, a pair of boots, portable lighting, and reflective vests, are some other important tools for the investigator. Finally, some basic hand tools such as screwdrivers, hammers, shovels, paintbrushes, and bolt cutters can help investigators to access areas thoroughly (Reno et al., 1999).

The Investigation Process

Analysing the crime scene

The first responder to arrive at the crime scene is usually a police officer and is in charge of the preliminary investigation. S/he has the responsibility of checking whether the suspect is still armed at the crime scene or in the surrounding area. The first responder must render medical assistance to any injured persons and be prepared to write down notes in case of any dying declarations. In case of the latter, the police officer must ask the right questions (such as built, race, hair and eye colour, clothing ect) to try to determine who the culprit is. Afterwards when the dead body is located, death must be confirmed. Thus, the victim’s pulse, respiration, and reflexes must be checked. Any witnesses should be identified and asked for personal details such as name, address, and mobile/telephone numbers so that they may be contacted later for investigative purposes. It is important that witnesses be separated in order to avoid discussion of the event of crime and thus, contamination of individual accounts of events (Truro Police Department, 2004).

The next vital step is to note all weather and environmental conditions, and to protect the crime scene and the evidence found in it until the investigation team arrives on site. This is done by isolating the crime scene from unauthorised persons and by verifying that no evidence is touched prior to the investigation team’s arrival on site. The first responder should also establish physical boundaries, park vehicles securely and safely, remove any animals from site, and control traffic. Scene safety is important for all the people involved in the investigation therefore such environmental and physical threats that can cause injury must be removed prior to the crime scene investigation. However, this should be done without damaging and contaminating the integrity of the scene and the evidence. In addition, it is important that the first responder keep a record of all the people that visit the scene, and only allow persons who are needed in the investigation (Reno et al., 1999).

Once the investigation team arrives on site, the first responder must report the details to them as accurately and fully as possible. Each member of the investigation team is assigned a specific task to make sure that all the area is covered adequately and to save time. A scene walkthrough should also be established so that entry and exits paths, physical and fragile evidence, and the deceased are identifiable. Depending on the number of investigators, a spiral, grid, linear, or quadrant pattern should be walked so that no area is left unsearched and location of evidence should be marked, photographed. and sketched. This is also essential to avoid alteration and contamination of fragile evidence that includes blood, body fluids (froths, substances from orifices ect), hair, fibres, and fragile evidence that is easily contaminated, lost, or modified. It is important that photographs and sketches indicate the location and patterns of all evidence that is to be collected, preserved, transported, and documented so that it can be admissible in court (Reno et al., 1999).

An accurate rough sketch of the crime scene containing the case number, location, and case name, can serve as a map to indicate the position and location of the body and any other evidence. All objects should be tied-measured according to stationary landmarks and measurements of the scene taken. A North indication is always appropriate to help understand the general layout of the sketch. If possible, a scale should be included to help calculate distances and sizes of objects. If the crimes scene is indoors, apertures and furniture should be included, whilst if the crime scene is outdoors, trees, fences, vehicles, or any other structures are to be sketched. Afterwards a finalised and accurate version of the sketch is to be drawn so that it can be presented in court. This can also be drawn using computer design software (Bertino, n.d.).

Photographic scene documentation helps in providing instant and permanent images of the scene that can be used to recreate the crime and when in doubt about certain details in the report, witness statements, and position of evidence. It is important to include a wide-angle view of the crime scene in order to make the location identifiable. Photographs should be provided with scales and taken at different angles to provide different views of areas. Triangulation of stationary objects should also be included in the photos as reference points. This will also help to uncover any additional evidence that is not noticed by the naked eye (Reno et al., 1999).

In addition, photographs with and without measurements, of the initial position of the body, the face of the deceased, objects removed, and the terrain beneath the body should be taken. This is essential to keep record of the position, appearance, clothing, identity, marks and scars, injuries, and final movements of the victim. A detailed record of the evidence such as weapons, cartridge cases, footprints ect, and any necessary measurements along with its relationship to the body should be taken. Volume, patterns, spatters, and other characteristics of blood and body fluids should also be recorded. This also applies for any odours, lights, temperatures, and other fragile evidence. It is important to note that whilst performing these tasks the condition of the body and evidence should never be moderated. Fingerprints, dental, radiographic, and DNA comparisons; personal belongings; photos of tattoos and physical characteristics can all aid in the investigation as these can lead to relatives if identification of the body is made (Reno et al., 1999).

The cause, manner, and time of death can all be determined from post mortem changes such as state of livor mortis and rigor mortis, degree of decomposition, insect and animal bites, and the difference between the temperature of the body and the environment. Documenting such details can help the investigator realise when the witness statements are corroborated and when the body of the dead was transported from a primary location. When the location of death is different from the place where the body is found, it is important for the investigation team to find such a place. Determining the location of death is important to discover how the body was transported to the secondary scene. This can be found by searching on the body and clothes of the deceased and for any drag marks and post-injury marks (Reno et al., 1999).

A record of the details of the person/s who discovered the body; the details of where, when and how the discovery was made; and the details of what was exactly was discovered is also necessary for the subsequent investigation and judicial processes. Documenting pre-terminal medical and mental records, and possible incidents and symptoms prior to death and obtaining the relevant ante mortem specimens is essential to determine the deceased’s condition before death. These also help in distinguishing between medical treatment/disease and trauma/injury, and thus determine the cause and manner of death. Marital, family, sexual, educational, employment and financial information, as well as any routines, habits, friends and associates of the dead all help to develop a profile of the deceased that will aid in establishing the cause and manner of death (Reno et al., 1999).

Furthermore, the investigation team is also in charge of making sure that the body is protected from further trauma and/or contamination; that all belongings and clothing of the dead victim are properly inventoried, that all evidence items are identified; that all blood and/or vitreous samples are collected; that the body in the body bag is correctly identified and removed from the scene; and that all of these are securely transported to the adequate laboratories and examining agencies. It is also the investigation team’s responsibility to notify all next of kin about the death of their relative and to record this (Reno et al., 1999).

Documenting and arranging for the secure transportation of body from the scene for autopsy or storage, maintains jurisdiction and chain of custody over the body by the investigation team. In fact, jurisdiction is only released when the body is given to the funeral director. The next step is to perform exit procedures to make sure that: all evidence has been collected, that no materials used in the investigation were left behind; and that all dangerous items were reported. Finally, the family should be informed of any autopsy and support services, and be given a timetable of events such as that of the time of body release and when the test results will be available (Reno et al., 1999).


Evidence can be either direct such as first hand observations of eyewitness testimonies and confessions or circumstantial. Circumstantial evidence is indirect evidence that may prove a link between the crime scene and the suspect. The latter can be divided into physical (fibres, weapons, bullets, shoe prints, blood) and biological evidence (body fluids, hair, plant parts, fingerprints and natural fibres). Biological evidence or individual evidence is many times preferred since this is likely to lead to a specific person, unlike physical evidence or class evidence that leads to a specific group of individuals (Bertino, n.d.).

After the evidence is collected from the crime scene, it is usually sent to forensic laboratories to be examined more closely. Test results are important for reconstructing the crime-scene, this means creating a hypothesis to explain the sequence of events from before the commission of the crime to its commission. The investigator should then determine how the evidence fits into the crime and compare it to witnesses’ statements. Evidence analysis is essential to determine the reliability of such witnesses, to identify suspects, to release any imprisoned innocents, and to verify if the crime scene has been staged (Bertino, n.d.).

Evidence such as fingerprints and biological samples from a crime scene can aid in the investigation especially if such biological information is loaded into a database. In this case, links between the new record and a pre-existing record can be established, thus ameliorating detection rates. Such information can then be used to arrest suspects and as evidence in court (Nuffield Council on Bioethics, 2007).


In cases where the cause and circumstances of death cannot be verified by the investigator or a doctor, the Magistrate in charge of the case may order an autopsy to be performed on the body by a forensic pathologist. An autopsy allows the examination of the dead person both from the outside and inside. This is done to examine any structural alterations, injuries, toxicological substances, and any other biological material such as blood, saliva, semen, and urine to find out the identity of the person and the cause, time and circumstances of death (“Chapter 8”, n.d.).


Sometimes in the investigation of a crime, searches in buildings, vehicles, and other locations as well as on persons must be conducted in order to look for and seize suspicious evidence. Such searches should always be conducted after the issue of a warrant from a Magistrate (Criminal Code Chapter 9, Articles 355E, and 355L (2)).


Witness interviews can be a good source of information for the investigation. Witness interviews should not interfere with human rights. In order to get as much information out of the witnesses as possible, the investigator should interview the witnesses as close to the event as possible to avoid the forgetting of certain details. It is better to create a favourable atmosphere to conduct the interview in order to make the witness as comfortable as possible. Calming down excited and upset persons and conducting the interview in a private and quiet area is also beneficial. During the interview, the investigator must write down notes unless video recording the whole conversation. Although spoken words are important, the investigator must also understand and record any body movements, emotional outbursts, and/or any sudden silence, as these can mean that further probing or clarification is needed on specific topics (Truro Police Department, 2004).

Since witnesses can turn out to be the culprits, investigators must be careful not to reveal important case information. Furthermore, it is also important not to ask close-ended questions so that the person is encouraged to open up to the interviewer. In fact when faced with a shy or reluctant witness, the investigator should try to persuade the individual to be truthful and to appear in court. Putting words in the mouth of the witness by asking leading questions and interrupting the witness constantly during the interview is also wrong since this could result in the witness narrating what the interrogator said rather than his/her account of events (New Mexico Survivors of Homicide, Inc.; Official website of the San Jose Police Department).

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Prior to the interrogation, Miranda warnings must be given to the suspect in an unhurried manner and in a way that s/he fully understands his/her constitutional rights. When an advocate is requested by the suspect, the interrogator must wait for such a person to arrive before initiating the interrogation. In cases of language barriers, underage persons, mental infirmity, influence of drugs or alcohol, wounds, and shock, waivers of Miranda warnings may be suppressed (Truro Police Department, 2004).

The interrogation of a suspect may be the only chance for the investigator to obtain an admission or confession. Thus, the investigator must establish a good rapport with the suspect regardless of the type of crime committed and the lack of remorse shown by the suspect. This means that no type of coercion, threatening behaviour or bribes shall be used to obtain a confession (Official website of the San Jose Police Department).

If the interrogator is lucky, s/he will get a voluntary confession that can be attained either in response to a question or by the free will of the suspect. In this case, the suspect should not be interrupted. On the other hand, if this is not the case, the interrogator should be tactful, patient, and reassuring whilst asking the questions. Furthermore, just like in witnesses’ interviews the interrogation is best conducted in a quiet and private room. Questions should be in simple and plain language, and asked consecutively without the use of sarcasm, interruptions, or suggestions of answers. A written record or video recording of all interrogations must be kept in all cases and must include the time and place of the interrogation and the names of the people present in the interrogation room (Truro Police Department, 2004).


In all stages of the investigation, the investigation team must keep a detailed report of each action undertaken in the course of the criminal investigation. All facts of the case must be reported since an investigation is only complete when it is accurately reported (New Mexico Survivors of Homicide, Inc.). An accurate report is important because without it, it is impossible to have a strong case against the suspect. All written records must include the name and identification number of the person taking action; the place, date and time of the action; details of the persons present; the case number; and the name of the suspect (“Chapter 8”, n.d.).

The report must include a summary of facts in narrative form (so that the reader can see a clear picture of the event before reading the whole report); a list of evidence listed according to size and using consecutive numbers for separate items (include: what, where, and from whom the item was seized, where it is being stored, and any other specifications such as if the item was used for testing and by whom); any processes that have to do with the investigation such as lab testing and search warrants; a list of witnesses, their testimony and connection with the case; copies of preliminary and follow-up investigation reports; statements of victims and perpetrators; background of deceased and defendants; examination results; photos; and status reports. However, the report should not include opinions of the writer and any other irrelevant material (New Mexico Survivors of Homicide, Inc.).

Follow-up investigations

Sometimes the initial investigation is not enough to close the case and as a result, follow-up investigations need to be conducted. This is many times done after the case report is reviewed and the investigator realises that additional evidence is needed. A follow-up investigation may include: additional interviews and interrogations; reviews of previous case records, analysing laboratory test results; obtaining information from informants; conducting other crime scene searches; checking criminal records for potential culprits; identifying and capturing suspects; and assisting in court prosecutions (Truro Police Department, 2004).


In cases where there is sufficient evidence that lead to one or more persons as being the perpetrators of the crime, the police have the right to arrest such person/s if in possession of an arrest warrant from the inquiring Magistrate. Arrests can be conducted inside or outside of a police station. However, if the arrest is performed outside the police station, the arrested should be taken to the nearest station and the inspector in charge must be informed (Criminal Code Chapter 9, Articles 355v, 355AE).

Court processes

Once the arrests are made and the investigation is complete, the investigator can present the case to the courts. If the evidence presented is sufficient and well organised to prove the guilt of a suspect beyond reasonable doubt, charges against the person are filed so that s/he will appear in court in front of a jury. On the other hand, if the evidence is not admissible in court, the case is rejected and dismissed. Therefore, it is in the hands of the investigator to compile a good casebook that will result in the prosecution and punishment of the culprit. After all this is the aim of an investigation to collect enough evidence, to identify and arrest the culprit, and to assist in the successful prosecution of the offender in a court of law (Official website of the San Jose Police Department).


(December 2012). New Mexico Survivors of Homicide, Inc. [On-line]. Retrieved from http://www.nmsoh.org/homicide_investigator_checklist.htm

(December 2012). Official website of the San Jose Police Department [On-line]. Retrieved from http://www.sjpd.org/BOI/homicide/glimpse.html

(n.d.). Chapter 8: Investigation of a criminal offense. Retrieved from http://www.usip.org/files/MC2/MC2-11-Ch8.pdf

Bertino. (n.d.). Chapter 2: Crime-Scene investigation and evidence collection. Retrieved from http://www.cengagesites.com/academic/assets/sites/4827/bertino_chapter2.pdf

Criminal Code. Chapter 9. Articles 355E, 355L (2), 355V, 355AE.

Nuffield Council on Bioethics. (2007). Chapter 4: Criminal investigation. In The forensic use of bioinformation: ethical issues (pp. 37-61). London.

Reno, J., Marcus, D., Robinson, L., Brennan, N., & Travis, J. (1999). Death Investigation: A guide for the scene investigator. Washington DC: U.S. Department of Justice, Office of Justice Programs.

Truro Police Department. (2004). Criminal investigation. Retrieved from http://www.truropolice.org/On%20Line%20Manuals/Criminal%20Investigations.pdf


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