In the frame of the COBRA (Conservation of Cultural Heritage through Radiation and Enabling Technologies) Regional project, several historical sites have been object of study by means of non-destructive techniques to analyze different kinds of artworks from different points of view, as structural modification or chemical degradation. The availability of information on the state of health of artworks quickly and as complete as possible can represent a great advantage for the optimization of the conservation and restoration actions. To this aim, several prototypes based on non-destructive laser based techniques have been developed at ENEA and encouraging results have been obtained by their application to some cases study supported by COBRA project. In this work, some results of the study of the Greek Chapel in the Priscilla's Catacombs in Rome performed by LIF (Laser Induced Fluorescence) Scanning, giving information regarding the surface chemical composition, will be reported. Particular attention has been devoted to the area indicated by the site referents as of special interest for the presence of an evident biological attack. In addition to the characterization of extended biofilms, LIF was also able to detect microorganisms from areas where biodegradation is not evident, suggesting the possibility of its early detection. This result can be of great usefulness for the site conservation. The analyses by standard laboratory techniques (e.g. microscope observations) prompt us to exclude the presence of photosynthetic microorganisms. For an easy and understandable vision of the obtained results, collected by different instruments, a post-processing and data fusion phase was needed.