Reconstructing a crime scene to gather solid evidence is all about having the right tools. To identify, mark, photograph and measure the ballistic trajectory of a projectile within +/- 5 degrees, choose products known for their quality and accuracy. Allen Miller explains the significant details of these five essentials in the trajectory reconstruction toolkit.
Look for kits like the Forensics Source Trajectory String Kit, recommends Miller, which contains a set of brightly colored red, yellow, blue and pink nylon string spools in a hard plastic insert with spool separators. Each with over 300 feet of string per spool, and notched holes on the string port to keep them separated during use, they can be tied down so they won’t unravel during transit.
Select from standard or deluxe configurations. The deluxe version, Miller notes, includes an additional 150 foot (45 m) spool of special reflective string which is ideal for outdoor night scenes as it reflects bright white when photo-flashed or illuminated with a flashlight.
Miller asserts aluminum or steel as the most accurate and effective trajectory rods. They can be connected in succession to three foot lengths using the included stainless steel connectors and maintain their rigidity over the distance.
Fiberglass trajectory rods are another standard in the ballistic trajectory toolkit with various options available. Lightweight yet preserving strength and durability, they are extremely versatile. The multiple colors aid in identifying multiple bullet paths, they can be centered in larger holes with spacer cones, and with the different tips (points or solid) can be used as penetration rods. Miller suggests the Multi-Color Forensic Rod Kit and the 48" Fiberglass Trajectory Rods both as practical choices.
Used to measure the angles of impact on a surface, protractors enable the zero line to be placed directly next to the evidence for accurate measurements.
A half protractor is ideal for placing in corners or other tight spots that are inaccessible to standard protractors. It features two built-in rulers, a six-inch ruler on the perpendicular base and a three-inch ruler on the face of the protractor. Measurements start at the bottom edge of the protractor, so accuracy is from the ground up.
Miller’s other recommended tool is a protractor with a laser mount. This 12-inch protractor has an adjustable arm which slides from 10 degrees to 170 degrees and can be locked into place once the correct angle is determined.
“The protractor ensures the measurements are accurate while the laser beam creates a consistent straight line without the possible sag of string,” Miller advises.
04ANGLE MEASURING TOOL
Miller recommends crime scene investigators invest in the EVI-PAQ® Bullet Trajectory Angle Finder. Used in conjunction with trajectory kits, investigators deploy the tool to measure the horizontal and/or vertical impact angles on a target. This information helps determine detailed, accurate statistics on where a bullet came from and its trajectory.
He also notes, when using the tool, it is important to measure in relation to the plane of the earth, not the plane of the impact surface.
The two best lasers on the market are the BP-1 Red Laser Trajectory Pointer and the BP-2 Green Trajectory Laser (built to the same exact standards as the more traditional red). Miller highlights that both lasers are co-aligned with their cases for consistent accuracy when conducting trajectory reconstructions, so the lasers do not deviate from their path.
Activation occurs when a steel connector or a trajectory rod is screwed into the base of the laser thus preventing accidental activation. Using both the laser and the trajectory rods in conjunction often will afford the investigator additional perspectives. For example, to demonstrate instances where a second shooter or second bullet path might impact or intersect initial evidence.
The EVI-PAQ® Laser Trajectory Kit is the most comprehensive option. The kit includes a choice of red or green laser trajectory pointers, tripod mount, four co-aligned steel trajectory rods suitable for use on holes produced by .32-caliber weapons and up. As well, connectors, spacer cones, O-rings and an angle finder round out the kit in a specially designed carry case and provide all the necessities for the reconstruction of ballistic trajectories. .22-caliber rods also can also be purchased.
EVI-PAQ® Standard Trajectory Kit provides the essentials without the laser option. Like the kit above, it contains a tripod mount, four co-aligned steel trajectory rods suitable for use on holes produced by .32-caliber weapons, connectors, spacer cones, O-rings and an angle finder. EVI-PAQ® Trajectory Kit Carrying Cases can be ordered separately.