Forensic Summary by Gina Gallucci
Thermal paper is chemical-coated paper that is heat sensitive and changes color when it encounters heat. It has become a common type of evidence in criminal trials as it used for cash register and credit card terminal receipts. Not only can the time and date be gathered from the paper, but latent fingerprints can also be developed. However, it poses a challenge because it changes color when normal fingerprint development techniques such as ninhydrin and 1,2-indanedione are applied. It was proposed that this could be avoided if the concentration of solution applied directly was altered.
Four polar solvents were used in combination with petroleum ether in varying concentrations to determine what did the least damage to the thermal paper. It was determined that ethyl acetate be used with 1,2-indanedione and that ethanol be used for ninhydrin as polar solvents as neither substance is soluble in petroleum ether. These both yielded fair florescent results. It is also suggested that combining them by first applying the 1,2-indanedione and then the ninhydrin solution will increase the success rate of development.
Chen, Chun-Chieh, Yung-Chien Yu, Henry C. Lee, Yun-Seng Giang, and Sheng-Meng Wang. “Latent Fingerprint Development on Thermal Paper Using Traditional Ninhydrin and 1,2-indanedione.” Journal of Forensic Sciences 61.1 (2016): 219-25. Web.