August of 2001, I was fortunate enough to attend the Administrative
Advanced Latent Fingerprint School at the FBI Academy.
One of the requirements of this course is that you do a research
project on a fingerprint related topic.
I chose “Development of Latent Prints on Adhesive Material”.
While researching the topic, I read an article that mentioned
using SPR in place of Sticky-Side Powder for processing electrical tape.
The reason for this was that it was somewhat easier to see than
the Sticky-Side Powder. I
mentioned this to Carl Keener, who was one of the instructors for the
course. He said that SPR is
nearly as dark in color as Sticky-Side Powder.
He mentioned that he had some of Sirchie’s white SPR in the
lab, but he had not had much success with it.
Sirchie’s white SPR comes in a liquid form, which contains a small
amount of titanium dioxide (TiO2), tergitol, and water.
When I tried using it on black electrical tape, it simply turned
the tape gray. I then added
some Kodak Photo-Flo to the SPR. I
processed a piece of electrical tape by agitating it in the mixture to
keep the TiO2 particles in suspension. After about a minute, I removed the tape and allowed the
mixture to drain off. Very
clear white prints were visible on the tape.
developed with TiO2 powder on the adhesive side of black
After returning to Albuquerque, I continued experimenting with this
process. Since TiO2 is
a common pigment in paint, I contacted a local company that makes paint
and explained what I was working on.
They gladly provided me with a large bag of Kerr-McGee CR-880
titanium dioxide. I found
that simply using the TiO2 powder in place of Sticky-Side
Powder produced excellent results.
three detail developed with
TiO2 powder on adhesive
side of black electrical tape
Mix the powder with a 50/50 mixture of water and Kodak Photo-Flo until
you have a paste. Apply it
to the tape, just as you would Sticky-Side Powder, but apply it to both
sides of the tape. Rinse
the paste off the tape and the developed latents will be visible. This process will develop latents on both sides of the tape.
Allow the tape to dry. The
developed latents will be delicate and can be easily wiped off,
especially on the non-adhesive side, so be careful.
This method works especially well on the adhesive side of
electrical tape and the non-adhesive side of duct tape.
If you are processing duct tape, I recommend processing the
adhesive side with Sticky-Side Powder and the non-adhesive side with TiO2
paste. The two processes
will not interfere with each other.
developed on the NON-adhesive side of duct tape
You can also make a solution in a tray to process larger items or pieces
of tape. Simply pour a
50/50 mixture of water and Kodak Photo-Flo into a tray and stir in TiO2
powder until the mixture looks like milk.
Agitate the item to be processed in the mixture for approximately
2 minutes, then rinse. Allow
the item to dry, then examine for developed latents.
processes also work well on plastic bags and cellophane.
must use a rutile form of TiO2, not an anatase form.
One of the best is Kemira 820.
It can be obtained from Steve Parker at Kalamazoo Paper Chemicals
for about $4 a pound. Contact
him via e-mail at KalPaperChem@compuserve.com.
I have successfully used this process many times
to develop workable latents on electrical tape, duct tape, and plastic
bags. Recently, one of our
Field Investigators, Kevin Sanchez, brought me a shattered car window
from the scene of an auto burglary.
The offender had apparently applied black duct tape to a window
of a Sheriff’s Department vehicle before breaking it.
He then took the shotgun out of the vehicle, but left the broken
window with the tape on it. I
left the tape as it was, still attached to the glass, and processed the
non-adhesive side with a TiO2 paste.
Numerous white prints of
AFIS quality were visible on the tape.
I immediately entered one print into AFIS, which hit on a
article on this process will be in an issue of the Journal of Forensic
Identification later this year. If
you have any questions, please contact me via e-mail at DWade@cabq.gov
or visit my website at www.whiteprint.com.