The second consideration concerns the possible failure of the proposed inspection method. In the previous section, we defined our criterion for considering successfully or unsuccessfully each single measurement.
Based on this criterion, it must be reminded that what we considered a ‘‘failure’’ of the method could be related to many factors as already pointed out (i.e. the quality of the donors and the particular considered thermal paper). As previously shown, in some cases we did not reveal fingermarks but these results could be obtained even after every treatment performed in a forensic laboratory which could not allow to reveal trace on forensic evidences.