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Projectile Path Reconstruction- Essential Elements

1.0 Objectives / Introduction

The objective of the following guidelines is to identify the essential elements

suggested for use in establishing training and procedure manuals as applied to the

determination of projectile paths from penetration or impact.

1.1 To recognize or identify techniques and procedures used in the

identification, reconstruction, and documentation of projectile paths based on

impact marks including penetrating, perforating, or non-penetrating points of

impact.

1.2 Projectile paths, for the purpose of this document, are determined from a

short segment of the entire trajectory path.

2.0 Definitions/ Terminology

Standard terminology should be used in the documentation of projectile path

evidence, from sources such as the Association of Firearms and Tool Mark

Examiners (AFTE) Glossary and the National Rifle Association (NRA) Fact Book.

2.1 Commonly used terms may include:

2.1.1 Ballistics: Internal, External, Terminal

2.1.2 Bullet wipe

2.1.3 Conical, Concentric, Radial and Rib glass fractures

2.1.4 Deflection

2.1.5 Incident angle, Departure angle

2.1.6 Keyhole

2.1.7 Perforation vs. Penetration
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2.1.8 Ricochet, Ricochet angle

2.1.9 Trajectory

3.0 Equipment

Proper equipment should be used and checked for

acceptable accuracy when appropriate.

3.1 Equipment and supplies may include:

3.1.1 String, cord or rope

3.1.2 Probes of various types and sizes

3.1.3 Laser devices

3.1.4 Distance measuring devices

3.1.5 Angle measuring devices

3.1.6 Leveling devices

3.1.7 Plumb bob and line

3.1.8 Calculator with scientific functions

3.1.9 Compass

3.1.10 Measuring tapes and scales

3.1.11 Safety equipment

4.0 Concepts

4.1 Projectile paths can be important in determining the physical origins of

gunshots, location of additional physical evidence and other general crime

scene reconstruction.

4.2 Over relatively short distances, projectile trajectories can be represented

by a straight line not withstanding deflection or ricochet. Therefore, readily

available aids such as string, probes and lasers can be used to illustrate or

document the projectile path.
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4.3 Points along a path may be delineated by penetrating, perforating, or

non-penetrating points of impact.

4.4 A projectile path consists of both the line and direction along which a

projectile travels.

4.5 At least two points of reference are generally needed to establish a path;

however, a single hole may sometimes be used to estimate a path based on

the associated shape, relative dimension, depth and/or trace deposits.

4.6 Direction of travel can sometimes be determined from the shape and

characteristics of an impact mark, as well as from bullet material deposition.

4.7 Caution should be used when attempting to determine the projectile

diameter from the hole or impact.

4.8 The angle of incidence and the angle of departure can sometimes be

estimated using the physical characteristics of the impact mark, and the

nature of the impacted material and/or projectile.

5.0 Procedures / Methods

5.1 Recognition of marks and holes

Care should be taken to preserve evidence associated with projectile

impacts as well as to avoid damaging the projectile during collection.

5.1.1 Documentation of visible characteristics associated with

marks and holes

5.1.2 Trace evidence associated with the marks, holes, or

projectiles should be considered

5.1.3 Chemical tests can be used to recognize impact marks or

holes as well as direction of fire, these tests may include:

5.1.3.1. Copper residue testing, e.g., dithiooxamide

5.1.3.2. Lead residue testing; e.g., sodium rhodizonate

5.1.4 Define coordinate system to establish a frame of reference

5.2 Path Determination

5.2.1. Probe method – suitable for relatively short distances
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5.2.2. String method – suitable for relatively short distances

5.2.3. Laser method – effective for distances or over terrain where

string or probes are not practical

5.3 Angle Determination

Angle determination includes both vertical and horizontal angles.

5.3.1 Direct measurement can be performed using a variety of

tools

5.3.2 Basic mathematical formulas can be used to calculate angles

where linear dimensions have been properly documented

5.4 Documentation

A variety of ways are available to document the projectile path relative

to fixed locations or relative to evidence items. These may include:

5.4.1 Sketching

5.4.2 Narrative description

5.4.3 Photographic

5.4.4 Audio or video recording

5.4.5 Measurements

5.4.6 Computer Assisted Programs

5.4.7 Computer assisted programs or software

5.5 Additional Factors for Consideration

5.5.1 Proper evidence collection techniques

5.5.2 Trace evidence

5.5.3 Environment e.g., terrain, physical barriers

6.0 Training / Qualification of Personnel

6.1 Training may include the following:
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6.1.1 Study of published materials and/or general procedure

manuals

6.1.2 Recognition and collection of firearm and ammunition

related evidence

6.1.3 Documentation techniques

6.1.4 Equipment use

6.1.5 Study under the guidance of experienced

mentors/examiners

6.1.6 Evaluation of known projectile paths during controlled

studies

6.1.7 Report writing and testimony preparation

6.1.8 Supervised or assisted crime scene investigation

6.1.9 Mock casework and testimony presentation

6.1.10 Formal Courses
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Appendix 1 - References

1. Courtney, M., and Hueske, E. E., “The Use of hand-Held laser Pointers in the

Reconstruction of Events at a Crime Scene – A Technical Note,” AFTE Journal,

Vol. 26, No. 3, Jul. 1994, pp. 170-172.

2. French, M. L., and Thompson, E. J., “Scene Reconstruction Using a Ballistic

Alignment Laser,” AFTE Journal, Vol. 29, No. 3, Summer 1997, pp. 372-374.

3. Theiling, D., “Bullet Deflection Due to Angled Intervening Materials,” AFTE

Journal, Vol. 33, No. 4, Fall 2001, pp. 304-312.

4. Roberts, J., and Hamby, J., “Reconstruction of a Shooting to Prove/Disprove

Trajectory,” AFTE Journal, Vol. 17, No. 2, Apr. 1985, pp. 53-55.

5. Trahin, J. L., “Bullet Trajectory Analysis,” AFTE Journal, Vol. 19, No. 2, Apr.

1987, pp. 124-150.

6. Lattig, K. N., “The Determination of the Point of Origin of Shots Fired Into a

Moving Vehicle,” AFTE Journal, Vol. 23, No. 1, Winter 1991, pp. 524-534.

7. Houde, J., and Cassidy, F. H., “Short-Range Bullet Trajectory Computer Program

for MS-DOS Computers,” AFTE Journal, Vol. 23, No. 3, Summer 1991, pp. 784-

791.

8. Warren, G., “Simple Measurement of Angles of Elevation,” AFTE Journal, Vol.

23, No. 3, Summer 1991, p. 869.

9. Nicolosi, F. M., “Ballistic Alignment Laser,” AFTE Journal, Vol. 24, No. 1, Jan.

1992, pp. 65-68.

10. Stone, R. S., “Calculation of Trajectory Angles Using a Line Level,” AFTE

Journal, Vol. 25, No. 1, Winter 1993, pp. 21-24.

11. Rathman, G. A., “Bullet Impact Damage and Trajectory Through Auto Glass,”

AFTE Journal, Vol. 25, No. 2, Spring 1993, pp. 79-86.

12. Hueske, E. E., “Calculation of Trajectory Angles Using an Inexpensive Angle

Gauge,” AFTE Journal, Vol. 25, No. 3, Summer 1993, pp. 231-233.

13. Haag, L. C., “Extended Ballistics Properties of Some Law Enforcement 9MM

Parabellum Cartridges,” AFTE Journal, Vol. 29, No. 3, Summer 1997, pp. 330-

345.

14. Bunch, S. G., “Some Proposals for Standardizing Trajectory Analysis and

Reporting,” AFTE Journal, Vol. 30, No. 3, Summer 1998, pp. 482-491.

15. Barr, D., “The Trig-Elliptical Method of Bullet Impact Angle Determination,”

Vol. 33, No. 2, Spring 2001, pp. 122-124.

16. Moran, B., “Case Report: The Reconstruction of a Double Homicide,” AFTE

Journal, Vol. 33, No. 2, Spring 2001, pp. 135-141.

17. Haag, L. C., “Reprint: Bullet Ricochet: An Imperial Study and a Device for

Measuring Ricochet Angle,” AFTE Journal, Vol. 21, No. 2, Spring 1989, pp. 182-

188.

18. Di Maio, V. J. M., “Wound Ballistics,” AFTE Journal, Vol. 4, No. 5, Dec 1972, p.

27.

19. Haag, L. C., “Reprint: The Use of Ballistics Calculations in the Solution of a

Crime,” AFTE Journal, Vol. 21, No. 2, Spring 1989, pp. 190-195.
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20. Haag, L. C., “The Forensic Use of Exterior Ballistics Calculations,” AFTE

Journal, Vol. 11, No. 1, Winter 1979, pp. 13-19.

21. Haag, L. C., “The Measurement of Bullet Deflection by Intervening Objects and

the Study of Bullet Behavior After Impact,” AFTE Journal, Vo. 19, No. 4, Oct.

1987, pp. 382-387.

22. Rathman, G. A., “Bullet Ricochet and Associated Phenomena,” AFTE Journal,

Vol. 19, No. 4, Oct. 1987, pp. 374-381.

23. Nennstiel, R., “Accuracy in Determining Long-Range Firing Position of

Gunman,” AFTE Journal, Vol. 17, No. 1, Jan. 1985, pp. 47-54.

24. Haag, L. C., “Vertical Ballistics,” AFTE Journal, Vol. 22, No. 1, Winter 1990, pp.

27-33.

25. Garrison, D. H., Jr., “Field Recording and Reconstruction of Angled Shot Pellet

Patterns,” AFTE Journal, Vol. 27, No. 3, Jul. 1995, pp. 204-209.

26. Nennstiel, R., “Detemination of a Line of Sight Angle Through Firing

Experiments,” AFTE Journal, Vol. 23, No. 4, Fall 1991, pp. 919-924.

27. Haag, L. C.., “Bullet Penetration and Perforation of Sheet Metal,” AFTE Journal,

Vol. 29, No. 4, Fall 1997, pp. 431-459.

28. Haag, L. C., “Sequence of Shots Through Tempered Glass,” AFTE Journal, Vol.

36, No. 1, Winter 2004, pp. 54-64.

29. NRA Firearms Fact Book, 3rd Edition, The National Rifle Association of

America, Virginia, 1989.

30. Association of Firearms and Tool Mark Examiners (AFTE) Glossary, 4th Edition,

AFTE, 2001.

Appendix 2- Revisions

Date Section Changes

9/28/12 Added Appendix 1 and 2