Crime Scene Processing

One of the most important steps in the scientific investigation of a crime is proper handling of the crime scene. For investigations to proceed in the right direction, crime scene responses need to be appropriate. The initial responders have a very responsible job of securing the crime scene in such a way so as to accelerate investigations. Even while facing dangers and risks, they strive to protect the crime scene evidences, while simultaneously making observations and tending to victims, suspects or both. While executing their job they require to remain alert, take decisions like the need for search warrants or backups, put up with onlookers, be responsible for personal safety all in line with established protocols.

Crime scene Investigator

 The crime scene investigator (CSI) also referred to as evidence recovery specialist is considered a forensic specialist within the criminology fraternity. He or she is responsible for the organized and systematic processing of the crime scene. The position requires expertise in the domains of recognition, documentation and management of physical evidences at the scene (Byrd Mike, 2000). The roles and responsibilities of the CSI vary from department to department and also on the geographic locations. For instance areas having a large population and high crime rate would require crime scene response as a full time job, while in low populated areas with low crime rates, crime scene response is only a part of other responsibilities. 

Classification of crime scene

Due to the diversity associated with crimes, crime scenes are classified in several ways. They may be classified as primary crime scene and secondary crime scene depending on the sequence of locations alone, and not on any other criteria. Another classification is the macroscopic crime scene and the microscopic crime scene, where macroscopic crime scene includes several crime scenes like a victims body left in a field, but was killed inside the house. Here the field, the house and the victims body are all part of a macroscopic crime scene. On the other hand, the microscopic crime scenes are individual trace evidences, like gun or tire marks, fingerprints etc. Crime scenes can also be classified based on the type of crimes like homicides, sexual assault, armed robbery etc. These can also be classified based on the crime scene conditions like organized crime scene or disorganized crime scene. The organized crime scenes are planned and executed while the disorganized ones are unplanned and impulsive with the crime scene being in disarray. The physical location of the crime scene is also use to classify crime scenes as indoor, outdoors or vehicle. However, despite so many classifications, no single classification can alone be attributed to any particular crime scene. 

Crime scene processing

Crime scene processing is a difficult and a long process, and it is inappropriate to suggest a typical crime scene or a typical approach. The Locards Principle of Exchange relating to a crime scene emphasizes that each time a person enters an environment something is left or taken from the environment. Every contact provides a trace, which holds good not only for contacts between individuals, but also between individuals and environment (Forensic Science, 2008). Crime scene investigators assume the amount and type of evidences left behind to be appropriate to the nature and situation under which the crime was committed. Physical evidences are like silent witnesses having in them the sequences of the crime. However it requires the investigator to put these in order to understand it. With evidences, investigators can recreate crime scenes and can justify or confront statements of witnesses, victims or suspects.

Normally the first responders to a crime scene are police officers, emergency medical personnel or personnel from the fire department. The importance of these first responders lies in the fact that they are the ones who see the scene in its original condition. Their conduct at the crime scene forms the basis for the successful or unsuccessful investigation of the case. While they perform their responsibilities, they should remember to take appropriate steps not to tamper with the evidences. Proper processing of crime scene involves three basic stage namely scene recognition, scene documentation and evidence collection.

Securing a crime scene

It is important for the responding officers, particularly the initial responding officer to be cautious while entering or exiting the scene of crime. Securing the crime scene is intended at minimizing contamination of the physical evidence. The first responding officer should be alert to any person or vehicles exiting the crime scene. Primary observations need to be made by sensing odor and sound to ensure personal safety. The entire investigation rests on the ability of the first responding officer to identify the scene and secure it.

The first responding officer should control, identify and remove people at the crime scene, so as to reduce entry and movement of people in the crime scene. The suspects and witnesses need to be secured and separated. The victims and their family and friends require to be controlled too, but with compassion. Such control contributes to the maintaining of the integrity of the crime scene while also minimizing contamination. A path for walking should be plotted. Once the detectives arrive, the responders need to direct them to the probable evidences and through the plotted way to get over there.

The responding officer should ensure that that none chew tobacco, smoke, eat or drink. They should avoid the use of telephones and as far as possible bathroom too (USDJ, 1999). The thermostat should not be adjusted nor the doors or windows opened, so as to maintain the scene in the way it was found. The responding officer should also consider the need to obtain a search warrant. While making sure that only one door is used for entry and exit of the crime scene, the first responder should maintain a log of the personnel arriving and departing with time. The responder must ensure that he or she doesnt touch anything and if anything has been touched, it has to be intimated to the CSI. 

A restrictive perimeter is established by a rope or similar barrier to restrict access. The boundaries need to be defined for protecting and securing the crime scene. The outer perimeter should always be larger than the actual crime scene.  The boundaries of the crime scenes and the number of crime scenes depend on the type of crime committed and their locations. While the boundaries stretch beyond the actual crime scene, the understanding here is that the boundaries can be reduced if required but cannot be expanded when desired. The established boundaries should have a central point and extend outward encompassing the crime scenes, entry and exit paths of victims and suspects, and the places they could have moved around.

The initial responding officer should be alert and call for backup or assistance if felt necessary. While ensuring the safety of victims and witnesses in the area, the first responding officer should also ensure the scene pose reduced danger for the officers. Once the dangerous persons or situations are brought under control, the initial responding officer should look into the medical requirements of the injured persons, minimizing contamination. He or she needs to assess the victim for signs of life and in case the victim is in a motionless state, provide required medical help including calling medical personnel. The responding officer should guide the medical personnel to the victim ensuring minimal or no contamination of the crime scene. The medical personnel need to be alerted to the possible evidence so that they can minimize contact with it. For instance the medical personnel should try to preserve clothing without tampering knife tears, bullet holes. The movement of the medical personnel and items need to be documented. The medical personnel are not supposed to clean up the crime scene or move or alter items at the scene. In case the medical personnel arrive first at the scene, the contact details of the attending physician, the agency he belongs to, need to be noted together with the name of the hospital the victim is taken to.  When the victim is in too serious condition and dying, a declaration might be attempted from him or her.  

First responder personal safety

All law enforcement officers including the first responder should be aware of the dangers of the crime scene and the ways they can be protected. The crime scene dangers include biological and chemical agents, fires and contamination. Blood based pathogens pose a big threat at most of the crime scenes. Every exposed biological matter including tissues, organs, blood fluids like semen and vaginal fluids, brain substances have a grave threat of disease transmission. Hepatitis B, C and HIV virus can be transmitted by used syringes or by air, as some diseases may be communicable by air. Chemical agents in clandestine labs are very powerful and may even be capable of explosions (USDJ, 1999).  The biohazards associated with the crime scene can be classified into four levels with the first being of minimum risk and the fourth bearing a maximum risk. Level 1 includes bacterial agents like E-Coli, level 2 includes Hepatitis B, C  and HIV, level 3 includes anthrax and tuberculosis while level 4 includes bovine fever,  E Bola  and other hemorrhagic diseases.

The first responders are the ones put in to bear maximum risk. Apart from securing the scene and verifying the incident, they also have to locate and tend to the victim or suspect, appropriately. The protocol for first responders requires them to avoid contamination risks. They need to be very cautious while approaching the scene and ensuring its safety.
Their protective clothing is their only gadget for protecting them from all harms. Their protective requirements generally include gloves, facemasks, overalls, shoe cover and safety glasses. For a minimum at least gloves and shoe covers are required to be worn by them. For crime scenes associated with chemical or biological dangers, HAZMAT suits, oxygen supply and breathing apparatus may be additionally required (Zarka Heather, 2007).

Scene recognition

An organized and legal determination of the scene is carried out to locate evidences. Factors like the area to be searched, number of searches, terrains etc. are considered to develop a pattern for the crime scene search. An operational plan is developed by an initial walk across the scene. The CSI and the first responder would survey the scene together. If available, the detective or lead investigator would also participate. The use of photography to document the preliminary findings would be helpful. The initial examination or survey as it is called, done by the investigator should ensure

Preparation of a theory reconstructing the chain of events, which should be altered according to developing situations and emerging new evidences.
Identification of evidences that require immediate processing or protection and provide the same.
Evidences are not affected by weather conditions, and to take protections when anticipated.

Documentation of crime scene

After a preliminary survey, the condition of the crime scene needs to be documented. The need of documentation is to produce a permanent record of the crime scene condition and the physical evidences. Crime scene documentation is a time consuming process requiring the first responder or investigator to be focused and organized throughout. The four major aspects of documentation are note taking, videography, photography and sketching. Each of these processes adds its own value to the investigation process, and therefore none can replace the other. It must be mentioned here that the need for documentation doesnt end, although it can be slowed down at times. There are several ways in which a CSI surveys the scene to document findings.

Inner spiral search In inner spiral searches, the investigator begins to search from the outer perimeter and works towards the center in a spiral fashion. These searches are appropriate when there is only a single investigator.
Outer spiral search In the outer spiral search, the investigator begins at the center and works outside spirally.

Parallel search Parallel searches involve several members of the investigating team to walk in a straight line. They cover the entire crime scene from one end to the other.

Grid search A grid search involves two perpendicular searches, performed sequentially by the investigation team.

Zone search In a zone search, zones are allocated to each CSI. They then switch their zones to ensure perfect coverage.

The activities undertaken with observations need to be documented as early as possible, which would be maintained as a personal record.  The documentation should include the position of items and individuals and their appearance and condition within the crime scene. The arrival conditions like the state of lights and fans, whether the doors and windows were open or closed, any particular smell etc. need to be noted. Comments and statements from victims, suspects or witnesses need to be maintained. While also emphasizing the actions performed personally or by others, the initial responding officers should document clearly his or her observations, which is valuable during subsequent investigations. 

Crime scene videotaping

A routine documentation procedure of crime scene is videotaping, which is widely accepted due to its affordability and ability to render a 3D description of the scene. The increasing acceptability trend and expectations in justice processes have only raised the role of videography in crime scene investigations. Crime scene survey is followed by videography, generally for orientation. The videotape should not show personnel of the crime scene team or their associates and their equipment. There should also be no narration or audio back up. Although videotaping is an important tool facilitating a clear understanding of the crime scene, which cannot be offered by any other means, it cannot be used as a substitute for any other processes too. The video should have details of the crime scene like date, location, time etc., which can be exhibited by a printed show card or spoken by the operator. Before the crime scene is shot, its surroundings, the roads and entrances of the scene are taped. It is necessary to use the four compass points as a guide. Within the crime scene, the evidence in relation to the complete crime scene needs to be taped. Wide-angle shots and close-ups of evidence pieces need to be taken too. A logical transition is to be maintained while shifting from one evidence to another, and not jumping from between evidences. The victims viewpoint requires to be taped too. By moving to a location close to the victim, the four compass points views of the victim needs to be taped.

Photographing of crime scene

 The need of still photography in crime scene documenting is to provide a correct and authentic record of the state of physical evidences through photos. Investigators and others now have records on the physical objects associated with the evidences and the evidences themselves in their original relationship. They serve as a permanent record for legal requirements. Crime scene photography is generally carried out after videography or preliminary survey of the scene. The general equipment of a crime scene photographer includes a camera, with 35 millimeter being very common, a normal lens, a wide angle lens, flash, tripod, black and white and color films, labeling materials, extra batteries, scale and photo log sheets.

An organized way of recording evidences through photography involves progressing from a broad perspective to a more focused one. This principle holds good when covering the crime scene or covering individual evidences within the crime scene. There are generally three types of photographs associated with a crime scene. These are overviews, mid-views and close-ups. The overview photos are shot focusing the entire area, covering the maximum scene. For indoor crime scenes, an overview shot provides views of each room, not just the room associated with the crime. Photos of the rooms are taken from every corner. The external views of the building in which the crime happened, showing all entrances and exits to the building, is also included. The particular building is also photographed with respect to its surroundings. Overview shots are also taken showing the spectators present at the scene. The idea in photographing the onlookers is that it could possibly have in it a witness or a suspect (Layton Julia, 2008). Most criminals return to the crime location and mingle with the onlookers after they commit it. The mid-range photos show individual evidences relatively. These photos enable understanding the location of evidence in a room and its association to other evidences.  The close-up photographs are again of individual evidences, but showing their prominent features like their serial numbers or any such identification. For close-ups, a tripod and lighting systems are used so as to achieve clarity. These photos provide great help when evidences are analyzed. A second set of close up shots are also taken, which have a scale marked.

Among the exteriors, which require to be photographed, are roads or paths leading to and from the crime scene. Survey numbers, signboards, mailboxes, should not be ignored. Whenever possible aerial photographs need to be taken, and if possible the exteriors could be photographed either before 10 am or after 2 pm (Miller Marilyn, 2003). For the interiors, the room corners or the four compass points are used as guide. When facing low light situations, use the tripod for better focus. While taking midrange photographs, a logical sequence is to be maintained. Flash lighting might be required when focusing on evidences individually, within the original view.  When taking close-ups, the placards should be used. Side lighting would be required with the flash used, when harsh shadows are present. The number of photographs required for any crime scene is not predetermined but that it should be of quality suitable for examination. While photographing, the investigator should never hesitate if a photograph of something requires to be taken or not. Photographs should always be taken whenever the worth of the object is doubted. It is important to ensure that the photographs are taken without moving or touching any of the evidences. Even the medical examiner to make the postmortem will not contact the corpse unless it has been photographed separately and with respect to its surroundings.

Each photograph of the crime scene must be properly mentioned in the photo log. The log entries should include the date and time of the photograph taken, the location, the corresponding exposure, the shutter speed of the camera and the distance at which taken. Photographs are very crucial to any investigation as they transcend any crime scene description with text and notes.

Crime scene sketching

As the photograph is a 2D representation of the crime scene, it cannot provide adequate or accurate information on the relative distance between the evidences. The relationship between the evidences cannot be understood without measuring them. There are also certain objects, which cannot be identified properly in the photograph. A crime scene sketch is a simple way of identifying important pieces of evidence with their actual orientation and measurements, at their location. The process of sketching provides a calibration perspective to the crime scene. Although sketching may not be difficult, it requires the investigator to plan and organize. Sketches involve a rough sketch and a final sketch. Crime scene sketching may be carried out with two perspectives namely an overview or a side view sketch. Sometimes a combination of both may be used too. Such a sketch is called a cross projection sketch. Although 3D sketches and scale models can be used in crime scene documenting, these are uncommon. Crime scene sketch measurements are obtained by three methods namely triangulation, base line and polar coordinates. Two starting fixed points need to be identified for all three measurements methods. These fixed points are permanent established points, which can even be referred later if scene reconstruction is required. Based on these two fixed points all other relative measurements are done. Notable fixed points include large trees, building corners, utility poles etc. 

Crime scene sketches are very much associated with documentation. This documentation includes a title or header, legends of abbreviations, letters, symbols used, whether drawn to scale or not etc. It should also mention the sketchers name, date and time of sketching, together with the case details. A crime scene sketcher might find it adequate with just a pencil, paper and a straight edged material, to prepare a rough sketch of the crime scene. However to make a final drawing, more-advanced equipment is necessary. To develop an outdoor crime scene incorporating the surroundings with adequate accuracy, the investigator should have been trained in geometry (Simmerman, 2009). Measurements in sketching are crucial. While sketching large areas, the accuracy should be in the level of yards while for smaller measurements, it should correspond to sixteenth of an inch. Measurements need to be taken personally by the sketcher, with his assistant only verifying them. Measurements of movable objects need to be established with respect to immovable objects. Although measurements may be established correlating immovable objects, there needs to be some measurements relative to immovable object. The orientation of the sketch must be properly indicated in the sketch. Determining the North direction with a compass it should be indicated within the sketch.

The sketch should highlight each and every evidence or items related to the investigation. However when unnecessary details are included, the sketch would look congested and is likely to hide important details. Therefore sketches should be simple incorporating only relevant information.
Surveying in sketching

When large areas are sketched, surveying methods might be required to make the sketch more accurate and easily comprehensive. When the sketcher doesnt have surveying knowledge, he should seek the services of a surveyor. Field sketching problems may be solved using coordinates methods like (Simmerman, 2009).

1) Rectangular coordinates Two mutually perpendicular lines might be used to locate points on a sketch. The mutual lines serve as reference points to which the objects in the crime scene can be matched. For instance a table in the crime scene might be located at 90 inches from the west side wall and 70 inches four the south sidewall. These can also be appropriately interpreted on a graph too.

 2) Polar coordinates A point or object within a crime scene can also be mapped by establishing its distance from a chosen origin and its corresponding angle with respect to a referential axis. It is mostly employed for outdoor scenes.  

Responding to sexual assault

One of the challenges faced by the crime investigators is in establishing rape. Since in most cases, the perpetrators are generally acquaintances of the victim, the investigation here is not directed to identify or confirm the perpetrator but rather to establish rape. Due to the close association of the victims and the offenders, the offenders would claim the act to be only consensual. Thus the investigation should be at countering this position. Regular offenders take such a stand and plead for mistaken identity. Physical injuries are very important in establishing rape against consensual sex (Estrich, 1987). This is an uphill task, as most rape victims dont receive considerable physical injuries, and absence of injuries tend to be considered as consenting. However forensic examination can highlight physical injuries that are associated only with rape, which forms solid evidence against the perpetrators.

Sexual assault victims need to be brought to a medical facility within 72 hours, and presented before a Sexual Assault Nurse Examiner (SANE). In case the victim is brought later, it would be beneficial if the victim has not showered or changed clothes. It is generally perceived that maximum evidences can be collected when the victim is brought before 12 hours from the incident. The investigation of rape includes a medical examination of the victim, carried out by a forensic medicine specialist.  The victims would mostly insist on an examination by their personal physician, which should not be accepted, as personal and general physicians dont have the experience in rape investigation, and also lack the ability to testify and to successfully get a conviction. The forensic medical examination is done interpreting the victims body as a crime scene. Minute physical injuries can be detected by new technologies like the colposcope, which are generally used by the gynecologists, for the observing of vulvar or vagina. A 30-time magnification of the injuries is provided by the colposcope, which helps in establishing genetic trauma to a very big extent. 


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