The crime scene sketch is a simple line drawing that indicates the position of the body in relation to fixed and significant objects in the scene. It supplements the written reports and the crime scene photographs. Because of camera perspective and distortion, photographs do not always depict the exact location in which objects are situated or the relation of one object to another. The crime scene sketch is an excellent visual aid, which allows for the removal of unnecessary details and the inclusion of significant material. Practically speaking, the homicide crime scene sketch can become one of the most useful tools of the homicide investigator.

The Sketch

A drawing of the crime scene is the simplest and most effective way to present measurements and to identify those items that the investigator deems significant, including the location of the victim's body, location of any physical or trace evidence, position of the weapon, and objects which may be significant to the overall scene. In addition, the drawing permits the deletion of irrelevant or distracting items which appear in photographs. In addition to creating a specific and selective diagram, the crime scene sketch can be used to

1. Refresh the memory of the investigator.

2. Refresh the memory of the witnesses.

3. Refresh the memory of the cooperative suspect to assist in detailing his or her actions at the scene.

4. Develop a clearer understanding of what happened and determine the relative likelihood of various possibilities. For instance, persons may be requested to trace their particular movements on copies of the original sketch.

5. Explain to a jury or witness the specifics of a case that may otherwise be too complex or confusing. The value of the crime scene sketch is that its clarity and simplicity motivate understanding.

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Figure 7.1 FINISHED CRIME SCENE SKETCH. Includes case numbers, dates and times, the identity of the drawer, and a legend. There is also an indication of point north. (Courtesy of Medical Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

The crime scene sketch should show the position of doors, windows, and staircases, as well as other objects of significance, including blood, weapons, stains, and any other trace evidence identified.

The rough sketch should be prepared by the investigator at the scene. He may use graph paper, which is excellent because it provides lines, or draw the sketch in his notebook. The most important element of the rough sketch is careful attention to measurements and distance. The ability of the investigator to draw is a definite asset; however, the rough homicide crime scene sketch need not be a Rembrandt production.

The rough sketch should contain a legend. The legend explains any numbers or symbols used and gives identification numbers assigned to the case, the identities

Figure 7.2 ROUGH SKETCH. This sketch is made in the investigator's notebook while at the scene. It is nothing more than a simple line drawing, which indicates the position of the body as well as objects of interest in the scene and gives measurements. Once again, there is an indication of point north. (Courtesy of Medical Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

of the sketcher and person taking the measurements, and a reference to compass direction north.

Many municipalities have a city engineer or graphic arts section with personnel who may, under the direction of the homicide investigator, prepare a professional smooth or finished crime scene sketch.

In some cases, an existing map or blueprint may be used to portray the crime scene graphically. I remember directing investigations involving homicides or shootings on New York City Housing Authority property. Because it is a city agency, the housing authority maintains blueprints of all properties under its jurisdiction. While at the scene, we obtained the blueprint of the particular project involved and

Figure 7.3 ROUGH SKETCH — CRIME SCENE. This is a rough sketch of the floor plan of the entire apartment of the preceding sketch. Any number of sketches can be prepared in any case. (Courtesy of Medical Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

used the blueprint as our crime scene sketch. Because a blueprint or map will already bear the scales and landmarks of the area, all the investigator need do is add the significant objects in the current case to the finished blueprint, being careful to measure distances and follow the scale provided in the finished plan.

It should be noted that the original sketch is evidence and, as such, must never be altered, changed, or otherwise tampered with after the investigator has completed his drawing at the scene. In addition, the investigator must assure that this original sketch is properly safeguarded even after a smooth or finished sketch is prepared by an expert draftsman. The original crime scene sketch must not be mutilated or destroyed. Often, especially in cases where the smooth or finished sketch is prepared for court presentation, the defense counsel will attempt to prevent its introduction or to diminish its value by demanding to examine the original

Figure 7.4 CROSS-PROJECTION SKETCH. All objects are drawn as if seen from above, but the walls are folded down and the items are drawn as if the room were a cardboard box with its sides flattened. (Courtesy of Medical Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

rough sketch. Defense counsel will then compare the rough sketch to the finished product and attempt to discover some inconsistencies or discrepancies.

Preparing the Crime Scene Sketch

Obviously, a determination must be made regarding what is to be sketched. If you are dealing with a single room, a line drawing or projection type of sketch may be employed. If the crime scene involves two or more rooms, you should used a simple line drawing, which follows a floor-pattern technique.

In order to assist the investigator in preparing the crime scene sketch, I have provided some practical examples and guidelines:

Figure 7.5 BASE LINE SKETCH. The base line method of sketching can be used when there is a scene without a convenient straight line or boundaries, such as a warehouse or large outdoor area. In this sketch, the cartons are moveable and the inside area large. By drawing a base line through the scene, you create a point of reference. Each end of the baseline should be identified and there should be a starting point or zero ends. (Courtesy of Medical Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

1. Necessary items:

a. Notebook, paper (8 1/2 in. × 11 in.) or graph paper with 1/2 in. squares, which can be used to scale feet (Remember to leave an ample margin for the legend.)

b. Soft lead pencil with eraser

c. Straight edge or ruler

d. Steel tape (preferably 100' length)2. Measurements:

a. All measurements must be taken from fixed points — for example, doors, windows, walls, chimney, stairs.

b. Measurements should be exact and should be taken with a steel tape or ruler.

c. One investigator should sketch while another officer takes the measurements.

d. In drawing the sketch, the investigator can estimate the relative distancesor positions of items because this rough sketch is not a scale drawing and artwork and technical detail do not need to be perfect. However, an accurate measurement should be taken and recorded in the sketch.

e. If distances are measured by pacing off, this should be indicated by thenumber of paces. (This procedure is not recommended, but may be used in the absence of proper measuring devices.)

3. Methods of obtaining measurements:

a. Straightline. Two measurements are made, one from each side of the object, to a fixed point in the diagram. This method is usually employed to mark positions of furniture or evidence along a wall.

b. Rectangular coordinates or perpendicular distance method. Two measurements are taken at right angles of an item to the nearest two permanent objects, usually the walls. This is the most practical method for marking the location of the body and other evidence. There are more accurate methods; however, I find this to be the simplest and most useful at the scene.

c. Polar coordinates or triangulation. By using a compass and a protractor, the investigator locates two fixed points and transfers this information to the sketch. Measurements are then taken from these two fixed points to the object, forming a triangle. Where the two points intersect is the exact location of the object.

d. Base line. This method is used for a scene that does not have convenient straight perimeter boundaries, e.g., a large wooded area or the interior of an expansive warehouse. A straight line is drawn through the scene, and each end is located and measured. A starting point is designated and the line is then used as a point of reference for all other measurements. The line can follow a seam or some other naturally existing line.

e. Two fixed points. This is a simple method whereby the investigator takes two straight-line measurements to two fixed points within the scene. There is no need for a right angle, but the two points used should not be close together.

4. The title block:

a. The professional and legally correct crime scene sketch must contain thefollowing official documentation and information:

1. The name and title of the investigator who drew the sketch

2. The date and time that the sketch was made

3. The classification of the crime (homicide, assault, etc.)

4. The identification of the victim

5. The agency's case number

6. The names of any persons assisting in taking measurements

7. The precise address of the location sketched

8. Reference points used during the sketching, including compass direction north, with appropriate indications

9. The legend. The purpose of the legend is to identify every article orobject by number or letter and explain the significance of these characters on the crime scene sketch. The legend also includes the scale used and a reference to any notes taken and measurements recorded in connection with the investigation.

10. Any other pertinent information practical to the investigation at thescene (for example, the season; the ground condition — muddy, dry; traffic or lack of traffic; slope of the ground; site — abandoned building, public place, transportation facility; the position of the camera in any crime scene photographs).

It is important to note that any number of crime scene sketches may be employed during the investigation at the scene, especially in multiple-crime scene situations.

Figure 7.6 SMOOTH SKETCH. Includes legend and objects, with a dotted line showing the path the killer took through the scene when he disposed of the body. (Courtesy of Medical

Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

Figure 7.7 STREET LOCATION SKETCH. This type of sketch is useful when dealing with several locations and pinpointing the movement of various persons. Symbols and letters can be used to show the movements of people involved. For example, V is the victim, A and B are the perpetrators, P represents the police, and W is the civilian witness. X is the crime scene. (Courtesy of Medical Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

Therefore, it is imperative that any sketch used be properly documented in the investigator's notebook along with descriptions and other pertinent information.

Utilizing Aerial Photographs for Mapping Outdoor Crime Scenes

Mapping and documenting a large outdoor scene can be very time consuming and tedious. A simple method that can be employed involves the tracing of aerial photographs utilizing standard graphics software such as Corel Draw Graphics Suite. The aerial photograph is scanned into the draw program. A "layer" is added to the photo (a layer is the equivalent of digital tracing paper), and the computer

Figure 7.8 AERIAL PHOTOGRAPH OF CRIME SCENE AREA. This is an aerial photograph of the area in which a homicide took place. This photograph was scanned into a draw program. (Courtesy of Detective John Brunetti, West Haven, Connecticut, Police Department.)

operator traces the items of importance. The tracing is perceptively as accurate as the photograph.

The investigator can search a variety of sources for up-to-date and accurate aerial photographs. City engineers as well as planning and development departments often have up-to-date copies of aerial photographs, which can be obtained for the investigation. Some situations may require pre- and postcrime scene aerial photographs. An example would be in a building explosion occurrence.

In addition, if no helicopters or airplanes are available to take overhead photographs, the local fire department can assist by providing an aerial truck for taking photos.

The "Total Station" Crime Scene Reconstruction Program

I conferred with Mr. David George, Survey Sales and Training, GeoLine Positioning Systems, Inc., in Bellevue, Washington, whose company distributes the Total Station units and software.1

Definition

What is a Total Station system? It is an electronic measuring instrument, combining an electronic distance meter (EDM) and an electronic theodolite, which records

Figure 7.9 PREPARING CRIME SCENE DIAGRAM OR MAPPING. A layer was added to the previous photo. The computer operator traced the items of importance. The tracing is perceptively as accurate as the photograph. (Courtesy of Detective John Brunetti, West Haven, Connecticut, Police Department.)

Figure 7.10 FINISHED STREET LOCATION SKETCH. This type of sketch is useful for court presentation to familiarize the jurors with the street locations within the immediate area of the event. (Courtesy of Detective John Brunetti, West Haven, Connecticut, Police Department.)

Figure 7.11 TOTAL STATION. The "Station" looks similar to a surveyor's transom; however, it is much more sophisticated. The instrument contains several internal components which perform various functions, and an external hand-held prism on a rod; the prism is placed at the location of the object to be measured. (Courtesy of Mr. Dave George, Geoline Positioning Systems, Inc., Bellevue, Washington.)

distance, slope, and horizontal and vertical angles to a given point. It is an instrument developed for use by surveyors and has been used by them for many years.

Operation

The Total Station looks similar to a surveyor's transit; however, it is much more sophisticated (see Figure 7.11). The instrument contains several internal components, which perform various functions. The system also can use an external handheld prism on a rod; the prism is placed at the location of the object to be measured.

The slope and distance are measured by an EDM that uses infrared light, which it emits in a beam. The beam of light pulses at a given frequency toward the prism. Once it reaches the prism, the light returns to the instrument. When the light returns from the prism, the "pulse" frequency has been changed slightly based on the distance traveled. The difference in the "pulse" frequency is calculated and converted into a distance measurement. Additionally, some Total Station models use a laser as the EDM. With these laser EDM instruments, the user does not need to use a prism to reflect the beam at distances up to 300 m. This allows the user to measure the distance from any object without needing to occupy the location directly.

The horizontal and vertical angles are measured by an electronic theodolite, which by definition is a surveyor's device for measuring horizontal and vertical angles with a small telescope that can move in horizontal and vertical planes. The horizontal angle is measured to the right or left relative to an established "zero" direction (called backsight or baseline). The vertical angle (or zenith angle) is measured relative to being level, with straight up being a "zero" angle and level being a 90° angle.

When the information is gathered by taking readings from the total station to the prism, it is recorded on a magnetic card, the internal memory of the instrument, or an external data collector by point number, along with a code describing what the point measured is — i.e., the head of a body, a gun, a knife, the right front tire of a car, etc.

The information can be recorded in several formats: "raw" data, which are the two angles and the distance; "coordinate" data, which are called northing (the difference in latitude between two positions as a result of movement to the north), easting (the difference in longitudinal distance from an eastern meridian), and zenith (zenith being the elevation); a combination of "raw" and "coordinate" data; and "tilt" or "offset" data. A code describing each point is entered and encoded by the operator. The code can describe an individual point or object, or it can describe the start of a line, skid mark, etc.; the number and type are limited only by the imagination of the operator. With newer external data collectors and software available, maps can be "drawn" in the field on scene with each measurement made. This allows the user to make sure the scene has been completely measured before leaving.

Why is the system called "Total Station"? What makes the system complete, and the reason it is called Total Station, is that once the data are collected at the scene, they can be downloaded into a computer. The addition of the computer element is what makes this system complete, thus the name Total Station.

Once the information is downloaded from the data collection device into a computer, via a card reader, several things can be done with the data. For example, software programs, which can be purchased separately, can be used to complete a crime scene diagram to scale for reconstruction or courtroom purposes.

Once the data are in the computer, several things can be done with them. First, and probably the most important thing, the data are stored in a "readonly file," which cannot be altered in any way. This is an important legal issue. The data can be retrieved at any time and worked with and refined; however, changes will be stored in a different file, never overwriting the original data file. Once the raw data are copied into a working file from the original file, the software calculates northing, easting, and zenith coordinates for each point, processes the codes as defined by the operator, and generates a "plot" file of what has been measured.

Once the plot file is generated, several things can be done with it. The file will be created with a .DXF file extension, which will allow it to be used in conjunction with various CAD (computer-aided design) programs, such as AutoCAD, EasyCAD, EdCAD, in two- or three-dimensional files, and/or certain computer animation files. The advantage to this is that the information can be output directly to a monitor (screen) or output to a plotter for a hard copy, or a disk file can be created for outputting at a later time. Some new CAD programs have been developed specifically for crash and crime scene mapping. These programs make it easier to develop final plots of a scene without the necessity of learning many different software programs.

Practical Application

The Total Station system is a new, modern, sophisticated way of using electronic equipment to take crime scene measurements. No longer are the familiar steel tapes and measuring wheels needed. Perhaps more importantly, no longer is it necessary to close down a roadway in order to take crime scene measurements.

Today, using the Total Station, an investigator sets up the instrument in a position off the roadway from where all the necessary points can be observed. The first measurement that the investigator takes after setting up and calibrating the Total Station is the end of a certified 100-ft steel tape. This is done as the first and last measurement to ensure the instrument is accurate for court purposes.

The investigators, working in tandem, then take the necessary measurements; one works the Total Station and the other holds the prism-rod. With some of the new Total Station prismless technology, investigators in a room can take measurements to location on a road without putting someone in harm's way or disturbing critical evidence. Research has shown that this methodology saves countless hours at the scene as well as later on when producing the necessary crime scene diagrams.

Once the measurements are taken and entered into the computer, an investigator can produce as many diagrams as needed to whatever scale is desired, with just the push of a button. Manual labor hours of producing a diagram are eliminated. Colored diagrams and color transparencies can also be produced by the computer. With the utilization of CAD, three-dimensional and animated reconstructions can be performed.

The Washington State Patrol had a case where a woman's body was found on the side of a cliff. Preliminary investigation had led investigators to believe the victim had committed suicide. However, by using the Total Station system in conjunction with the crime scene measurements it recorded, investigators were able to prove the incident was a murder because the body had to be thrown off the hill onto the side of the cliff for it to be in the position in which it was found. Without the Total Station, a murderer would have gone free and a family would have unnecessarily suffered the stigma of a suicide, not to mention the loss of insurance money.

Figure 7.12 TOTAL STATION CALCULATES THREE-DIMENSIONAL COORDINATES.

The drawing here represents the sophisticated Total Station system's ability to take crime scene measurements. (Courtesy of Medical Legal Art. Illustration copyright 2005, Medical Legal Art, www.doereport.com.)

For further information about this crime scene documentation technique, contact:

GeoLine Positioning Systems, Inc. (425) 452-2700

1331 118th Avenue S.E., Suite 400 Bellevue, Washington 98005 www.geoline.com

Reference

1. George, D. Personal interview, September, 2004.

Selected Reading

Gardner, R. Practical Crime Scene Processing and Investigation. Boca Raton, FL: CRC Press, 2005.

Geberth, V.J. Practical Homicide Investigation: Tactics, Procedures, and Forensic Techniques. 3rd ed. Boca Raton, FL: CRC Press, 1996.

The Homicide Crime