General Study Guide - Ontario Police College

Titanium Dioxide (prints develop on non-adhesive and adhesive
sides)
White
Chemical reaction – see separate article in this study
guide for additional information.
From OPC Notes for developing prints on “Balled Tape”…
Tape may be separated for examination by heat, freezing or solvent.
1) Heat method – Use hair dryer at low or medium setting
2) Freezing method – Place tape in freezer until frozen solid or use a
pressurized can of air sprayed directly onto the tape.
3) Solvent method – Use “Shandon Xylene” developed by the U.S. Army
Criminal Investigation Laboratory. Under a ventilation hood/fuming
cabinet & using gloves & eye protection, hold the tape with tweezers and
use an eye dropper to apply very small amounts of the solvent to the
tape at the line of adhesive. This method has also been effective in
removing adhesive tape from paper or cardboard.
Caution - Impression may be damaged from transfer of
cells during separation of tape.
Using the solvent method, fingerprints have been
developed not only on the tape but also on the paper
from which it was removed. The tape was examined
using Crystal Violet and Ninhydrin was used on the paper.
Developing Latent Prints on Tape – non-adhesive side.
Proper development sequence and types of chemical processes – depending on the circumstances not all processes may apply. All processes, however,
are post visual and examination of inherent fluorescence by laser and alternate light source.
Latent Print
Development Techniques and ‘Basics’ of Processing Procedure
Development Colour
Ridge Detail Visualized By
Cyanoacrylate Fuming
To protect adhesive side, place tape on a piece of clear acetate before CA.
Vacuum Metal Deposition (see page )
White
Fumes from the active cyanoacrylate ester
polymerizes eccrine components of the
print residue. Post-cyano dye stains &/or
powders are used to further enhance the
developed prints. Refer to separate table
for a list of possible dye stains and
appropriate forensic light sources.
Powder
Dependent on choice of
colour.
Contrast made between powder colour and
substrate.