Shooting Reconstruction by iPhone
Written by Edward E. Hueske   

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IN ORDER TO CARRY OUT shooting-incident reconstructions in the field, the examiner needs a fairly large array of equipment. The requisite equipment items include a compass, digital calipers, laser protractors, a plumb bob, and a zero-base protractor. Being able to record atmospheric conditions is desirable, particularly at outdoor scenes. A theodolite, while not absolutely essential, speeds up the process and provides highly accurate results when measuring the height of objects and relative angles at shooting scenes.

When trying to document and reconstruct a scene, it can be a problem (to say the least) when you realize you do not have all the necessary tools at hand. Luckily, the modern age of technology stands ready to come to the rescue. If the examiner has an iPhone (3GS or newer) and is willing to spend a total of about $6, there are two applications that offer rather amazing capabilities.

These iPhone apps include:

Real Tools, a suite of electronic iPhone tools from Bahn Tech ($1.99) www.bahntech.com/iphone

Theodolite from Hunter Research ($3.99 for the Pro version; also available in both Free and Basic versions) hunter.pairsite.com/theodolite/

Ballistics Calculator, an app from Winchester Ammunition that provides standard external ballistics information that can be useful when long-distance shots are involved (Free) www.winchester.com/ballistics

These apps may be used without any necessary iPhone accessories, but the theodolite is best if used with a clear plastic case for the iPhone, an “L” bracket, a tripod mounting block, and some Velcro so that the iPhone may be mounted on a tripod.

These tools have proven to be both useful and accurate in field tests, but, for the most part, they are presented here as backups for the “real thing”.

A virtual toolkit

The proper documentation of crime scenes in general and shooting scenes in particular requires a multitude of equipment items. A listing of the minimum required equipment would include the following:

Angle gauge; compass; digital caliper; GPS unit; laser protractor; level; plumb bob; measuring scale; scientific calculator; thermometer; trajectory rods of various diameters and related accessories; and a zero-base protractor.

Ideally, the examiner would also have access to a theodolite system (total station) for measuring distances and angles and mapping scenes.

The Real Tools app, combined with the Theodolite app, turns an iPhone (3GS or newer) into a veritable “Swiss army knife” for trajectory analyses in shooting-incident reconstructions—including all of the tools on the list above with the exception of trajectory rods and related accessories.

Measurement of trajectory-rod angles

A trajectory rod inserted into a bullet path has two angular components generally designated as angles x and y. Both the Real Tools app and the Theodolite app offer the means to measure these angles. The Real Tools app offers both a standard protractor as well as a “laser” protractor. Since the standard protractor is not zero based, the examiner must make sure to use the 0/180 line as the base. The Theodolite app allows an image to be recorded while the Real Tools application requires external imaging.

Recording compass position


Image 1 - Compass in the Real Tools app.


Image 2 - The iPhone's accelerometer allows you to use it as an electronic plumb bob.


Image 3 - Electronic level, Real Tools app.


Image 4 - Weather station, Real Tools app.


Image 5 - Metric ruler, Real Tools app.


Image 6 - iPhone on tripod, Theodolite app.


Image 8 - Global Positioning System.

The iPhone has a built-in compass feature that provides a large digital readout. The Real Tools version is a little more difficult to read, given the smaller digits that appear. The Real Tools compass is shown in Image 1 (on page 28). Placing a compass in the field of view is a useful form of documentation of the orientation of bullet holes in horizontal substrates.

Electronic plumb bob

When trajectory rods have been inserted into vertical substrates with irregular contours, it is necessary to establish a plumb line to use as a reference standard for the vertical angular component of the trajectory being represented. The Real Tools application has an electronic plumb bob that may be used for that purpose. This can be accomplished while handholding the iPhone and using the edge of the case to position a zero-base protractor as illustrated in Image 2 (on Page 27).

Electronic level

The Real Tools app offers two different styles of levels. Additionally, one can use the electronic angle gauge when leveling is necessary, such as in photographic documentation of evidence items. The Theodolite app offers both horizontal and elevation angles that may be viewed simultaneously, facilitating tripod-mounted camera orientation with a substrate. One of the available levels can be seen in Image 3.

Documenting atmospheric conditions

A very neat “weather station” can be found in the Real Tools app that provides not only temperature, but also barometric pressure, humidity, dew point, and wind speed. As one should expect, this information is valid outdoors only. An example appears in Image 4.

Measurement

The Real Tools app provides a digital caliper for taking measurements of items small enough to fit on the iPhone screen. Approximation is necessary with the object, such as a bullet, being placed on the screen and the jaws of the calipers moved until a “good fit” appears to have been achieved. There is also a metric ruler the length of which is the width of the screen (7.55 cm). This is illustrated in Image 5.

Theodolite

One of the most impressive iPhone applications is Theodolite from Hunter Research and Technology. This app provides position coordinates, altitude, elevation angles, horizontal angles, azimuth angle, and compass bearing. All of this is interfaced with the camera so that images of interest may be recorded.

The Theodolite application allows distance from A-B elevations, height from A-B elevations, A-B delta angles, A-B distance headings, and point C from A-B triangulation to be determined. This is best accomplished with the iPhone securely mounted on a tripod. An illustration of a tripod mount is shown in Image 6.

Global Positioning System

The GPS tool in the Real Tools app provides both a map and digital coordinates as shown in Image 8. As with the weather station, the system works best outdoors. The Theodolite app also offers similar information.

Scientific calculator

The iPhone comes with a scientific calculator for calculating trajectory angles, among other things, that may be accessed by touching the calculator button on the main screen and then rotating the iPhone 90 degrees.

Other useful features

In addition to the above capabilities, some other useful features can be found in these systems. There is a battery meter in the Real Tools app that provides pertinent information as to the battery status of the iPhone. This is important due to the rapid rate of battery depletion that results from use of these applications. There is also a flashlight utility that provides light of various colors in addition to white light.

Ballistics software

An additional application of value for shooting-incident reconstruction is ballistics software. Recognizing the popularity of iPhones, Winchester Firearms Company has recently released a ballistics program for the iPhone that may be accessed at their website and downloaded for free from Apple’s App Store. This software provides the field investigator with instant access to typical external ballistics data such as bullet path, time of flight, line-of-sight drop, and wind drift that can be useful in some aspects of shooting reconstruction, such as those involving long-range shots.

Discussion

It is unlikely (and unadvisable) for one to consider trading in the traditional shooting-reconstruction tools for the electronic counterparts described here. However, there are certainly advantages to having the capability of the pocket-sized versions. As always, the crime-scene examiner must be prepared for a wide variety of circumstances and equipment demands.
When one combines all these capabilities into the small package presented by an iPhone and then considers the relatively small cost, it is nothing short of incredible. This technology is something every field investigator should have as part of their “bag of tricks”.

About the Author

The author, This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , is the Criminalistics Program Coordinator with the Department of Criminal Justice at the University of North Texas.

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