LD 30 - Crime Scenes, Evidence, and Forensics

inner perimeter

Designated area which contains specific evidence of a crime and is under the control of law enforcement officers

outer perimeter

Designated area which surrounds an inner perimeter and is used as a means of securing and controlling access to an inner perimeter

preliminary investigation

begins when the responding officers first receives the call. It continues through the writing and filing of the primary officer's investigative report.

Diagrams

crime scene diagram is a measured drawing showing the location of all important items, particularly items of physical evidence. A crime scene diagram should show the: • layout of the entire scene, • measured locations within the crime scene of each piece of evidence, • locations of significant features of the scene, & • spatial relationship between items. Diagrams may be included with the officer's investigative report.

Rough sketches

crime scene sketch is a rough drawing created by an investigating officer @ the crime scene. It contains details & measurements that will be used when the final accurate diagram is later drawn. Rough sketches should be included in an officer's field notes. A crime scene sketch should: • be drawn @ the crime scene, • be complete enough to stand alone, & • include measurements pinpointing the location of all major items of physical evidence & critical features of the scene (e.g., furniture, plants, personal possessions, etc.).

Transfer evidence

evidence that is transferred or passed when two objects touch.

Trace evidence

evidence that is very small; it usually cannot be seen with the naked eye without close scrutiny.

investigation

the systematic gathering of information from a variety of sources & the documentation of evidence, observations, & findings. Law enforcement agencies conduct a variety of different types of investigations including, but not limited to: • background investigations (e.g., screening job applicants), • internal investigations (e.g., regarding conduct of officers), • permit investigations (e.g., prior to issuing business licenses), & • criminal investigations.

Search Patterns

• Line, • Quadrant, • Grid, • Spiral, • Wheel.

Types of photographs

• Location, • Witnesses, • Evidence, • close-ups.

Metal (Containers)

• chemicals or • items with flammable fluids on them (e.g., gasoline soaked rags). • Small tins, larger containers, etc. • Should be airtight & sturdy enough to prevent leakage or easy damage • Other packaging materials should not be included within the can (e.g., paper, bubble wrap, etc.).

Cardboard (Containers)

• firearms or • items that need protection such, as: • bloody clothing or • knives or other weapons with dried blood or tissue on them. • Boxes, flat pieces, etc. • Item should be carefully placed in an appropriate sized box.

Glass (Containers)

• liquids that are not compatible with metal. • Bottles, vials, etc. • Can break easily (thicker glass is preferable), • Should be airtight.

Plastic (Containers)

• paper or, • small amounts of narcotics or drugs. • Bags, containers, etc. • Do not use with items that are wet or damp and could mildew quickly. (Plastic is nonporous & will not allow air to get in.)

large, bulky, or heavy (packaging evidence)

• place the item on wood or heavy cardboard. • prevent shifting & contact with other items by fastening the item down firmly with string or wire passed through perforations in the supporting material. NOTE: Organic plant materials should be packaged in paper (e.g., marijuana).

Followup investigations

• reviewing the original report to develop additional leads. • viewing all evidence seized and ensuring submissions to a crime laboratory. • conducting follow-up interviews with the reporting officer, victim(s), witness(es), and suspect(s) • evaluating statements, evidence, and laboratory results. • gathering additional evidence through surveillance. • identifying, locating, arresting, or seeking warrants for the arrest of suspect(s). • conducting custodial interviews. • compiling and conducting field showups and lineups. • seeking warrants for searches and recovering stolen property. • maintaining a liaison with the prosecutor. • complying with victim/witness obligations

small, light weight, or fragile (packaging evidence)

• wrap the item lightly with soft paper, taking care not to damage any evidence. • place the item in a small box or other container, as soon as possible, for transport.

Paper (Containers)

Most Dry items: * Sheets, bags, envelopes, etc. * Best type of container to use * Easy to store * Allows items to "breathe" * Easy to write on * Can be transferred to other containers, if necessary * Organic plant material (e.g., marijuana, mushrooms)

Common Errors (Handling Evidence)

Most common errors made in the handling of evidence @ a crime scene include the failure to: • identify items of possible evidentiary value, • use the appropriate techniques for properly collecting a specific type of evidence, • submit sufficient quantities of evidence, • protect evidence from contamination, • submit control/known standard to be used for comparison purposes, & • maintain the chain of custody.

Perishable/ fragile evidence

1st officers @ a crime scene should immediately observe & record any evidence that could be easily lost, damaged, contaminated, or destroyed by environmental elements or the presence of other individuals at the scene. Such perishable/fragile evidence should be noted, photographed, documented, & collected 1st. Examples of evidence include, but are not limited to: • fingerprints, • biological fluids and stains, • gunshot residue, • paint • hairs & fibers, • flammable liquids & accelerant, • shoe, foot, or tire impressions, etc.

Submitting evidence

After each collected sample has been properly photographed, collected, marked, packaged, & labeled, it is ready to be transported to the local property room or office & "submitted into evidence." @ that time, the evidence becomes the responsibility of the property & evidence manager. Agency policy will dictate which items may be recorded on a single property form. The property form becomes the chain of custody record for that item, documenting when, why, how, & by whom the item has been handled.

Chain of custody record (continued)

Although the format of property forms may vary, each will require specific information including: • report number, • who initially found the item, • where & when the item was found, • a description of the item, • who recovered, packaged, & labeled the item, • who transported the item, • where it was submitted, & • where, how, & when the item was secured.

custodial arrest

An arrest in which the suspect will be transported to a law enforcement facility such as a station, jail, or detox center

Chain Of Custody Definition

Chain of custody is the written, witnessed, unbroken record of all individuals who maintained control or had access to any physical evidence. A complete & accurate chain of custody record is absolutely essential in establishing the validity & integrity of evidence in court.

Precautions (handling Evidence)

Collection of evidence should proceed slowly & cautiously, no evidence should be overlooked or compromised. Prior to beginning the actual collection process, officers should consider: • photographing evidence to demonstrate its appearance when found. • diagraming the location and position of items of evidence to aid in later reconstructions of the scene. • taking notes regarding the physical appearance of evidence to document the condition in which it was found. • wearing appropriate clothing such as disposable gloves & nonrestrictive, noninterfering clothing.

Benefits of Photographs

Crime scene photographs can: • provide investigators with a visual record of the crime scene. • allow the court to visually see the crime scene & the position & the state of each item of evidence @ the scene. • serve as a means of preserving fragile evidence. • be stored as evidence indefinitely & be readily available if needed @ a later time.

Photographs as evidence

Crime scene photos are often used in court as a form of demonstrative evidence. photos may be admissible as evidence if they: • show an object or person relevant to the crime, • accurately represent, without distortion, the object or scene photographed, • are marked properly to identify contents & location, & • are not used solely to appeal to the emotions or prejudice the court or jury.

Benefits of Crime Scene Sketches & Diagrams

Crime scene sketches & diagrams can: • display a crime scene as a whole or in part. • provide clear & concise descriptions of all pieces of evidence. • show the relationship of items to each other. • show measured distances between items. • illustrate positions & movement of involved parties (e.g., victims, suspects, witnesses). • provide a permanent record of the conditions not easily recorded in words. • aid in reconstructing the crime scene. • supplement written field notes. • assist the reporting officer in writing comprehensive investigative reports. • illustrate the crime scene without extra clutter.

Handling Evidence

Evidence can take any size, shape, or form. It may be obvious or imperceptible to the naked eye. Even if an item may not have obvious evidentiary value to an officer, it should be properly secured & identified.

Content Elements of

Final crime scene diagrams should include specific types of information: • Diagraming Officer, • Other Individuals, • Time, • Crime Identification, • Details, • location & position, • Other Info.

Chain of Custody

For any piece of evidence to be considered valid & reliable by the court, it must be accounted for from the time it is collected @ the scene until it is presented in court.

Involved individuals - preliminary investigation

Individuals involved in the investigative process may include, but are not limited to: • reporting parties, • responding officers, • investigating officers, • victims, • witnesses, • evidence technicians, • medical examiners, • forensic scientists, and • attorneys.

Court testimony

Individuals within the judicial process who have handled a piece of evidence (e.g., investigating officers, evidence technicians, etc.) may be asked in court to positively identify that evidence & testify regarding: • who had contact with the evidence, • when or during what time periods the evidence was handled, • under what circumstances the evidence was handled, & • what changes, if any, were made to the evidence.

Photographs

Photographs of a crime scene can record exactly how the scene appeared & how the evidence was found @ the scene.

Packaging evidence

Physical evidence can be damaged, lost, contaminated, or changed during handling & transportation. All pieces of evidence must be carefully packaged separately, using new & clean containers & packaging materials.

Search plans

Prior to conducting a crime scene search, all involved law enforcement personnel should have a clear understanding of the search plan. Everyone assisting in the search for evidence should be made aware of the: • type of crime that has taken place, • type of items that may be associated with the crime, • perimeters of the area to be searched, & • searching pattern that will be used.

Areas to examine

Searching officer should examine the object or area from an angle. Possible areas or objects to examine may include, but are not limited to: • suspected points of entry or direct contact (e.g., window sills, broken glass, door or metal associated with hit-&-run cases, etc.). • points of direct contact (e.g., furniture, carpeting, bedding, or clothing).

Locating trace & transfer evidence

Special considerations may arise when searching for trace and transfer evidence @ a crime scene. Search techniques may include: • examining the area carefully using: • the naked eye, • a magnifying lens, • oblique lighting (e.g., flashlight held at an angle), • using an evidence vacuum, &/or * specialized light.

Equipment (handling evidence)

The ability to properly collect & preserve evidence may depend on officers having access to the appropriate equipment. A basic crime scene equipment kit may include, @ a minimum, the following items: • Camera Equipment, • Measuring Equipment, • Documentation Materials, • Lighting Equipment, • Collecting Equipment, • Packaging Equipment, • Specialty Kits or Equipment, • Other.

Chain of custody record

The chain of custody begins when an item is 1st collected as evidence. From this time, supplying complete, clear, concise information & using appropriate documentation techniques will aid in keeping the chain of custody intact.

Documentation (Crime Scene Surveys & Searches)

The condition of the crime scene along with the location & description of items of possible evidence identified during any search should be documented in: • the officer's field notes, • photographs, • crime scene diagrams, & • the officers original report & other supplemental reports.

corpus delicti

The established body or elements of a crime

initial survey

The first sweep of a crime scene; allows responding officer(s) the opportunity to establish the kinds and amount of evidence that exists and the amount of time, equipment and personnel that will be required to process the scene

Selecting a search pattern

There are a number of search patterns that can be used when attempting to locate evidence @ a crime scene. The selection of a search pattern used @ a crime scene should be based on the: • location & configuration of the crime scene, • number of personnel available for the search, & • personal preference.

Types of trace & transfer evidence

There can be numerous types of trace & transfer evidence @ a crime scene. Examples include, but are not limited to: • hair, • fibers, • soil, • paint chips, • glass fragments, • biological fluids, etc.

Sealing evidence

To maintain the chain of custody, each container containing a piece of evidence should be properly sealed. Evidence tape can be used to seal all containers (i.e., boxes, envelopes, vials, etc.) in such a way that they cannot be opened without breaking the seal. The person packaging the evidence should sign or initial & date the seal using permanent ink so that the marking extends from the seal onto the container.

Marking & labeling evidence

Using permanent ink, the following info should be carefully & legibly noted on the evidence label or tag. • Collecting officer's name • Collecting officer's identification number (i.e., serial/badge number) • Time & date the evidence was collected • Location where the evidence was collected • Content description (including quantity & size) • Type of crime (e.g., burglary, homicide) • Any other related information such as: • case control number, or • witness(es) to the collection, • Collecting officer's signature.

probable cause

When the totality of the circumstances causes a person of ordinary care and prudence to entertain an honest and strong suspicion that the person to be arrested is guilty of a crime

Contamination

When two objects touch each other, it is possible for trace substances of one to be transferred to the other. For example, whenever an individual enters a crime scene, it is possible for that individual to introduce physical evidence to the scene (e.g., fibers, hair, fingerprints, etc.) as well as to remove physical evidence from the scene (e.g., fibers on clothing, soil on shoes, etc.). Such transfers can take place not only to potential suspects, but also peace officers who enter or leave a crime scene. For this reason, crime scenes must be carefully protected and secured from any intentional or unintentional forms of contamination.

Crime Scene Sketches & Diagrams

While photographs capture the position & state of individual items of evidence, they do not offer a "bird's eye view" of the layout or the relative position of items of evidence. Sketches & diagrams can be used to supplement photographs & provide this additional information regarding the crime scene.

fingerprint

a copy or impression of the ridges & valleys present on the outermost layer of human skin. These ridges & valleys can be found not only on the tips of the fingers, but also below the first digit & sides of fingers, & on palms, feet, & toes. Each pattern that makes up a fingerprint is unique to that specific individual. These patterns 1st appear on human appendages between 100 & 120 days after conception &, except for size or some form of external permanent damage, will remain the same throughout the person's lifetime.

criminal investigation

a systematic approach to the: • establishment of a criminal violation, • identification & arrest of a suspect, & • gathering of evidence for presentation in a court of law. The ultimate goal of any criminal investigation is the successful prosecution of the guilty & the exoneration of the innocent.

crime scene search

a systematic, coordinated effort conducted in order to: • locate physical evidence that indicates a crime has taken place, and • identify individual(s) who may have committed the crime.