Crime Scene Searches
This ALL OFFICERS BULLETIN is a training method to discuss topics and updated material of general interest to all personnel. The information is not department policy or regulation. It is being presented as a job performance aid; to inform, create awareness, and encourage self improvement in the day to day discharge of police service.
Police Department 220 Clay Street Cedar Falls, IA 50613
The procedures used in the search of the scene of the crime or accident are determined by the need to evaluate three basic factors concerning evidence: What evidence can be recovered which will aid in determining what happened and that may further identify the suspect/s? How can evidence best be preserved so that it is not lost, altered, or contaminated? How can the identification, collection, and preservation of the evidence best be recorded so that it remains admissible in court?
The situation encountered by the law enforcement officer at the scene of an investigation will often require that certain steps be taken before a search for evidence begin.
Stabilize the Situation
If the action is “in progress”, or if people at the scene are injured or hysterical, the responding officer may have to administer first aid, make an arrest, or take other steps to bring the situation under control. This is most important! Without ultimate control of the scene, personnel may be ineffective in the investigation and subsequent search for evidence. Additional assistance may be necessary. Personnel should not overextend their ability to control the situation. If assistance is on the way, specific assignments should be given to the responding unit(s) while in route in order to avoid confusion and unintentional intrusion into the area. If it is necessary to open a lane for traffic, whether for pedestrians or vehicles – search it first. Ignoring this step may result in missed or otherwise ignored evidence. Clear the area of everyone not actively involved in the investigation. Erect a barrier, place cones, and take other measures necessary to avoid contamination of the scene. Be aware of the surrounding area, as evidence may be located some distance from the scene. Burglars often discard tools in flight. Protect all areas in which you feel evidence may be located.
Obtain the names and addresses of everyone at the scene as soon as possible. Witnesses should be separated in order to minimize the potential that they may influence one another’s observations. Briefly interview those present to gain a general idea of what they may have observed. In the event a potential witness refuses to produce identification, or the officer believes the person may take flight, steps should be taken to taken to determine if the person may be lawfully detained. When applicable, record the descriptions and license numbers of motor vehicles passing through the area. Take overall photos of the scene as soon as possible before anything is added, altered or removed from the area. It is essential that these photos show as close as possible the scene as it was at the onset of the investigation. It is further advised that witnesses, onlookers, and law enforcement personnel remain clear while these photos are being taken. Do not however forget that it is sometimes advisable to photograph onlookers at the scene. (It is a proven fact that arson suspects often stay in the area to view fire fighting efforts and the resulting damage.) Make a basic sketch of the scene. It will then be possible to record the location of evidence as it is being seized. Graph paper with one-quarter inch squares is ideal for this purpose.
Planning the Search
The search of the scene must be methodical in order to minimize the chance of overlooking potential evidence. This requires a plan. The planning done in the field takes little time, but it requires a knowledge of what is likely to be found and how to search for it. Many of the better crime scene investigators have a pre-designed checklist at their disposal to aid them in remembering necessary steps that need to be taken. Often, events at a scene are going on simultaneously and rapidly – thus increasing the chance of overlooking something important. Slow down! Evidence recovered at the scene will generally vary in the type and location found from incident to incident. Evidence recovered at a safe burglary will differ from that recovered at the scene of a hit and run fatality. While at the scene, officers should ask themselves these questions: What happened? How did the scene get to be as it is now? What looks out of place? Is there evidence that may help identify the perpetrator? By answering these questions, the investigator may develop a tentative idea about what happened. The scene which appears to be a suicide by initial observations may in fact be a homicide – or accident. An effort should be made to reconstruct a probable order of events which may have lead up to the incident. Many criminals follow a similar general sequence when committing a crime: They first approach the scene in a vehicle or on foot. They enter the immediate area. The crime is committed. They leave the immediate area. Finally, they flee the general area.
Impact and Exchange
An investigator is most likely to find useful evidence when he or she has some idea of what they are looking for and how they may best preserve the evidence. The physical characteristics of the location of the incident are altered by a process of impact and exchange. The burglar impacts the crime scene by breaking glass at the point of entry. Exchange occurs when fingerprints are left behind on pieces of the glass which are removed from the window frame. Exchange may also occur when fragmented glass is embedded on the suspects clothing. The evidence of this impact and exchange is the best possible. It not only places the criminal at the scene, but it connects the criminal to the incident itself.
Organization is the key to a successful search – to a search that recovers all the evidence to be found at the scene. In order to ensure a thorough search, a well organized pattern should be followed. A number of search patterns have proven to be successful, and three of them are identified as follows:
Zone Method. This type of search is most often used in small areas, such as houses or apartments which lend themselves to be divided into specific areas, such as rooms, stairways, and corridors. Each zone can be sub-divided into sub-zones, such as floors, ceilings, or closets. Strip Method. This approach is particularly useful in searching a large area. The scene is divided into parallel strips and a searcher is assigned to each strip. The method is useful in searching the scenes of motor vehicle accidents where the scene is often narrow, yet spread out over several hundred feet.
Grid Method. This search also is useful at larger crime scenes. The method incorporates two overlying strips, which divide the scene into a grid. An open field would be a good example of an area suitable for a grid search.
Be methodical. By sticking to any search pattern, there is less likely a chance that an area will be skipped. Once an area is searched, it is always advisable to have it searched again by another investigator. An effort should be made to be particularly aware of trace evidence. Small items such as fingerprints, hairs, fibers, and blood are often overlooked or destroyed, yet they are often the best evidence. The investigators should be constantly aware of evidence which could change what was an initial theory regarding the incident.
Protecting the Evidence
When evidence is located, it is often advisable to first call attention to it for documentation purposes prior to its seizure. This documentation is necessary due to the highly fragile nature of some evidence. Evidence can be fragile due to one or more of the following: passing time, exposure to the elements, improper handling, and movement. In some instances at which fragile evidence is encountered it may be necessary to take control of the evidence immediately. The otherwise orderly search pattern may have to be temporarily abandoned in order to document and seize evidence which could be effected by any one of the factors described as making evidence fragile. (see above) A footwear impression in a highly travelled area may have to be photographed or casted. Skid marks at an accident scene may have to be measured and documented. In special instances such as these, it is essential that the evidence be given special attention with immediate documentation and seizure.
Documenting the Evidence
When an item of evidence is to be marked on a basic sketch being prepared by the investigator, it’s exact location can be indicated by showing the distance of it from two fixed points. In lieu of drawing the item, the evidence can be placed by assigning it a letter or number and listing it in a table or legend elsewhere on the sketch. When evidence is located, it is important to immediately record the find. Varying agency policies or the seriousness of the offense may dictate that the documentation of the evidence be witnessed by a second investigator. One advantage to having a witness is that future courtroom testimony may be possible by one of the investigators in the absence of the other. Most agencies have a system of numbering evidence in order to keep a record or sequence of findings. It is best to assign numbers to the evidence while at the scene to avoid later confusion when all the evidence has been collected and transported to the holding facility. In addition to assigning evidence numbers, it is further advisable to prepare a complete inventory of all evidence seized during the investigation. Copies of this inventory should be available to the agencies evidence custodian and case file, and to the prosecuting attorney.
Marking and Packaging
All evidence should be marked by the seizing investigator by placing identifying markings such as date and time of seizure, the location found, or the officers initials on the item. This should of course be done only when it can be accomplished without endangering future examinations by an evidence examiner if and when it is necessary. More often the packaging in which the evidence is placed can be marked with this information and then sealed with tamper proof evidence tape. Package and label each item separately. Label each package clearly, even when the item itself is marked. This then makes identifying the evidence possible without opening the packaging. Items of evidence vary greatly so a variety of boxes, bags, or bottles may be used. When packaged, the evidence should be protected from breakage or other unnecessary damage. The following are a few suggestions for packaging types of evidence: Blood stained clothing should be AIR DRIED (without the use of hair driers or fans). It should then be packaged in paper bags, or packaging paper, (not plastic). Cardboard boxes may also be used. Glass containing possible footwear markings or fingerprints should be air dried when applicable; then placed in an appropriate container such as a cardboard box. If possible, separate the individual pieces with layers of paper to avoid cross – contamination. Hairs, fibers, and other trace evidence should be placed in a pharmaceutical fold and sealed with evidence tape to prevent leakage. As noted above, paper bags are preferred over plastic because they “breathe” and do not promote the growth of micro-organisms which can render blood and other types of biological evidence useless.
Chain of Custody
The prosecutor must be able to prove that any item offered as an exhibit is in fact the object found at the scene or during it’s subsequent investigation. This requires a complete record of the chain of custody from the time of it’s seizure, showing the identity of all persons having possession of the evidence at any given time. Evidence sent to another agency for examination should be done so by registered mail, so a record of whom the evidence was received by can be produced.
Pitfalls of Crime Scene Searches
Damage done by Police Officers
Accepting the scene at face value and jumping to conclusions
Ignoring the obvious
Disregarding evidence which seem unrelated
Failing to collect all of the evidence
Reassessment of the Scene
Once the scene has been abandoned it becomes history and there is little or no opportunity to regain what may have been overlooked. The investigator should take the time to reflect on the activities taking place while at the scene. Questions to ask as the investigation progresses should include: – Does all of the evidence fit the theory developed by the trained investigators present? – Was there evidence which was expected to be found, but wasn’t? – Was unexpected evidence encountered? If any of these questions raise an uncertainty in the mind of the investigator, a false assumption may have been made, or the scene may have been improperly processed. Try to resolve conflicts about the findings while still at the scene where the search can be continued if the need arises.