Forensics Journal - Stevenson University 2011 | Page 59

FORENSICS JOURNAL

In testing the two week old depletion series, sufficient ridge detail
was visualized on the substrates under the appropriate light source
on the evidence bag, the red bubble wrap, the red Coke can, the
multicolored birthday bag, and the black trash bag. Figure 5 shows a
fingerprint developed on the red Coke can. The left side of the image
was developed with Greenwop and the right side with upconversion
powder. The Greenwop developed a much clearer, detailed print, but
the busy background overpowered the print. The background is more
suppressed on the upconversion half, but the print is barely visible.

Upconversion versus green fluorescent powder
The substrates used in this research were allowed to age for varying
periods of time before cyanoacrylate fuming and powdering with
Greenwop (green fluorescent powder) for its comparison to the
upconversion powder. Four trials of the varying ages of prints were
performed to compare the upconversion powder to the green fluorescent powder. In the 1 ½ week old depletion series, fingerprints
were developed and seen with enough detail to photograph on the
PP sheet protector, the red Coke can, the bubble wrap, the black
trash bag, and a multicolored birthday bag substrate. Figure 4 shows
a print developed on a multicolored birthday bag where the left side
was developed with Greenwop and the right side developed with the
upconversion powder. The upconversion side appears overdeveloped
with parts of the print obstructed by the excessive amount of powder
and uneven distribution over the ridges.

The three week old depletion series developed fingerprints with sufficient ridge detail for photographing on the zippered “Stor-it” bag,
PP sheet protector, PVC sheet protector, evidence bag, black trash
bag, black pebbled surface, multicolored birthday bag, and fold top
sandwich bag. The fingerprints in the 4 ½ week old depletion series
were fairly degraded and had evaporated to a certain degree. Prints
were developed on the Coke can and the birthday bag, but much of
the ridge detail had deteriorated or was destroyed during the development process. Due to the heavy nature of both the Greenwop and the
upconversion powder, there were many instances when one half of the
fingerprint was developed, but the other half of the fingerprint was
not developed.

FIGURE 4: Print #6 of a 1 ½ week old sebaceous depletion series
developed on a multicolored birthday bag. The left side is developed
with Greenwop powder and the right side is developed with the
upconversion powder.

Scanning Electron Microscope (SEM)
The commercial powders (non-magnetic, magnetic, and fluorescent)
as well as the upconversion powder were analyzed using a Scanning
Electron Microscope in order to determine the overall morphology
for a better understanding of what makes the powders different from
one another. Black carbon powder (non-magnetic) had thick rounded
flakes with a particle size ranging from 20-33 µm. Figure 6 shows
the particles of the black carbon powder as being flaky with no sharp
edges. The white powder (non-magnetic) appeared as light, grainy
particles with a particle size ranging from 0.55 – 0.85 µm, which
is a very small size in comparison to the other fingerprint powders.
The black magnetic powder had a similar appearance in particle
shape to the black carbon powder, but the black magnetic flakes have
sharper edges. This magnetic powder had a particle size ranging from
11-18 µm. The particles of the white magnetic powder are thick and
clumpy, appearing “heavy” in nature. The size of the particles ranges
from 100-160 µm. White magnetic powder contained the largest
particles compared to the other five fingerprint powders, yet remains
a very effective development tool. The green fluorescent powder
(Greenwop) particles appeared as perfect spheres with geometrical
indentations spaced around the outside similar to a soccer ball. These
particles ranged in size from 1-2.5 µm. The upconversion powder had
varying sizes of particles that clumped together. These particles ranged
in size from 30 µm to 35 µm. Figure 7 shows the particles of the
upconversion powder as being very clumpy and heavy.

FIGURE 5: Print #2 of a two week old eccrine depletion series developed on a red Coke can. The left side is developed with Greenwop
and the right side is developed with upconversion powder.

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