Sources of Error
Thirty-five items were chosen that could be found in each of the nine
rooms in the game Clue. A fingerprint was put on the each item. A
powder was chosen that would provide contrast to the color of each
item. A brush was used to spread powder across the items to develop
the fingerprints. If a magnetic powder was used, the brush was waved
across the surface so that the powder adhered to the print.
If a print could not be found using the powder
chosen, another powder was used to see if a print would become
visible. Ninhydrin was used to develop a set of prints on paper in
order to compare the quality with prints on paper developed with
powders. In many cases, silver powder was followed by chemist grey
powder because silver powder got into the ridges and filled them too
much. Chemist grey powder was used to clean the ridges out and develop
Hinge lifters were used to lift the print for
viewing and storage. A hinge lifter was chosen that was either clear
so that different lighting effects and background colors could be used
or that provided contrast to the color of the powder used. The hinge
lifter was placed on the print and pressed down evenly. A roller was
sometimes used to ensure a smooth lift. The lifted print is covered
with the hinged cover and is protected from scratches and dirt. If the
item had a rounded or oddly shaped surface, clear tape was used for
the lift because hinge lifters donít bend around surfaces without
bubbles or creases.
If fluorescent powder was used, the print was
viewed under an alternate light source. Photographs were taken of all
the lifts for computer viewing and a magnifying glass was used to
examine each of the lifts.
Observations were recorded for each of the items.
These were used to explain the quality of the lift and the reason each
developing technique was used.
A shoeprint was also developed. Vaseline
was spread on the bottom of the shoe and the shoe was pressed onto a
sheet of white paper. Magnetic powder was waved over the surface of
the shoeprint and adhered to the Vaseline, giving a developed
A quantitative evaluation system was
developed in order to give each of the prints a quality number. Prints
were viewed closely and a quality number was assigned based on the
quality, clarity and identification possibility of each print.
Graphs were made using various combinations of the data in order to
evaluate the different developing techniques, item surfaces and
quality numbers. These graphs were also used to evaluate the
effectiveness of the Quantitative Fingerprint Evaluation System.