1. Unit 16 - Firearms, Tool Marks, and Other Impressions

2. imperfections

3. imperfections
The presence of minute imperfections on tools imparts individuality to that tool.

4. Further imperfections
The shape and pattern of such imperfections are further modified by damage and wear during the life of that tool.

5. Further imperfections
The shape and pattern of such imperfections are further modified by damage and wear during the life of that tool.

6. Comparison microscope
The comparison microscope is used to compare crime scene two marks with test impressions made with the suspect tool.

7. Comparison microscope
The comparison microscope is used to compare crime scene two marks with test impressions made with the suspect tool.

8. tire tracks

9. tire tracks
Shoe and tire marks in pressed into soft earth a crime scene are best preserved by photography and casting.

10. electrostatic lifting
The electrostatic lifting technique is particularly helpful and recovering barely visible dust prints on floor surfaces.

11. electrostatic lifting
The electrostatic lifting technique is particularly helpful and recovering barely visible dust prints on floor surfaces.

12. electrostatic lifting
The electrostatic lifting technique is particularly helpful and recovering barely visible dust prints on floor surfaces.
a sheet of mylar film is placed on dust mark.

13. electrostatic lifting
The electrostatic lifting technique is particularly helpful and recovering barely visible dust prints on floor surfaces.
a sheet of mylar film is placed on dust mark.
film is pressed to mark using a roller

14. dust impression
A dust impression of a shoeprint on cardboard after chemical enhancement with Bromophenol Blue and exposure to water vapor.

15. dust impression
A dust impression of a shoeprint on cardboard after chemical enhancement with Bromophenol Blue and exposure to water vapor.

16. Chemical enhancement
Chemical enhancement can visualize latent or nearly invisible blood impressions In areas where a bloody foot where impression

17. Chemical enhancement
Chemical enhancement can visualize latent or nearly invisible blood impressions In areas where a bloody foot where impression

18. Chemical enhancement
Chemical enhancement can visualize latent or nearly invisible blood impressions In areas where a bloody foot where impression
very faint

19. Chemical enhancement
Chemical enhancement can visualize latent or nearly invisible blood impressions In areas where a bloody foot where impression
very faint
where the subject was track to blood

20. Chemical enhancement
Chemical enhancement can visualize latent or nearly invisible blood impressions In areas where a bloody foot where impression
very faint
where the subject was track to blood
leaving a trail of blood impressions