It is important to point out that in our study we were not interested in
the comparison of different reagents or different methods for the
detection of latent fingerprints. We were focused on the proof of
principle for a new inspection method that can be always applied
when you deal with thermal paper and we aimed to show that this
method works. For these reasons we did not need to follow rigidly all
the steps foreseen by the protocols that can be found in literature
[15]. In our study the latent fingermarks were impinged on the
collected thermal papers by different individuals (n = 3) of unknown
donor capabilities. Individuals were requested to wash their hands to
make them free from any greasy matter and after half an hour asked
to rub their hands in order to make homogeneous the content of the
fingerprints. After these preliminary operations, they impinged
sequentially for three times their latent fingermarks on thermal
paper samples. These were labeled as eccrine fingermarks. Individuals
were further requested to impinge another set of fingermarks by
‘‘charging’’ the finger tips by gentle rubbing of the same against
cheeks or forehead. These fingermarks were predominantly sebaceous.
In this way, two sets of latent fingermarks from each individual
were obtained. The described operations were repeated for two times.