Latent prints can be used as evidence in crime scenes to connect individuals to the location of a potential crime. In some cases, perpetrators may handle partially eaten fruits at the scene of a crime and leave latent fingerprints on the surface of the fruit. Plant leaves of common household ornamental plants and regional shrubs may also be a potential source of latent prints. Fruits, vegetables, and plant leaves have not been extensively studied as substrates for fingerprint development. In order to assess the feasibility of developing and visualizing latent prints on fruits, vegetable, and plant leaf surfaces, black and white fingerprint powder, bi-chromatic magnetic powder, and LumicyanoTM superglue fuming were utilized on tomato, zucchini, cucumber, acorn squash, carrot, mango, plum, pear, orange, pepper, banana, watermelon, Rhododendron leaf, Philodendron leaf, and Jasmine leaf. An aging study up to sixteen days was also conducted on eight of the fifteen substrates to determine the effects of aging on latent fingerprint impression development. Latent prints were recovered from all surfaces with the three techniques. Using a scoring system of 0-2, in which 2 represents the presence of six or more minutiae and 0 represents the lack of minutiae, impressions developed with fingerprint powder scored the highest average across all substrates. The aging study revealed a general decline in the quality of the latent prints over time with LumicyanoTM fuming performing the best.

For the past several decades, challenges in the detection and collection of latent prints exposed to harsh environmental conditions have inspired research in pretreatment methods prior to the application of chemical, physical, or optical-based enhancement techniques. Some of the difficulties associated with processing degraded latent prints are attributed to dehydration, alterations in chemical composition, and physical disturbance of ridge detail. This study seeks to investigate the effectiveness of humidity, cyanoacrylate fuming method (CFM), and a reflected ultraviolet imaging system (RUVIS) on the detection and collection of aged latent palmprints. Prints were exposed to air flow and ultraviolet (UV) light for a period of 0 to 28 days, and subsequently treated with either cool or warm humidity and CFM. RUVIS was then utilized to detect and capture friction ridge detail after each treatment step. Improvements in RUVIS detection between treatments were evaluated based on four response factors: minutiae count, percent print recovery, ridge thickness and contrast. By measuring these factors, each latent print photograph was able to be converted to quantifiable data to facilitate statistical analysis of potential differences or improvements between treatments. The results demonstrate that the application of 80% relative humidity successfully revived aged latent palmprints across all factors. The combined effect of humidity followed v by CFM treatment and RUVIS detection was greatest for minutiae count and ridge thickness, while percent print recovery and contrast demonstrated more modest improvements when compared to control prints. Additionally, cool temperature treatments outperformed warm temperature treatments across all factors except contrast. The data therefore suggest that to achieve print rejuvenation and overall improvements in RUVIS detection, combined cool humidity and CFM is more effective than humidity alone. The data also indicate a potential correlation between temperature treatments and latent print age. Warm humidity combined with CFM appeared to best enhance RUVIS images on fresher prints of a few days to one week old, while cool humidity and CFM appeared to maximally enhance RUVIS images on prints of several weeks old.