Rehydration and restoration of fingerprint ridge detail in mummified post-mortem tissue: Literature review and investigation of a simplified formulation.

Mummified tissue presents challenges for fingerprinting due to rigidity, shrinkage, and other features obscuring epidermal ridge detail. A new cost-effective in-house solution was developed to obtain good quality fingerprints from mummified remains. The simplified procedure uses a sodium carbonate:sodium acetate mixture easily prepared using commonly available chemical products. An overview of the methods and solutions utilized to date for rehydration and restoration illustrates the main benefits of the developed formulation: the solution provided better tissue pliability and turgor than the sodium carbonate:ethanol formulation of Rüffer previously employed; the prepared solution proved stable for weeks at room temperature and poses minimum hazard risk to users. It functions as a weak base (pH 9.3) and is sufficiently corrosive to allow tissue softening over a flexible timeframe of 1-5 days without causing any damage. The degree of effectiveness for rehydration of mummified tissue and restoration of ridge detail is attributed to three synergistic aspects: increased turgor as provided by a penetrating humectant and water; softening and pliability as a result of pH and any specific chemical interaction that affects calcium in collagen; ridge detail definition as a function of turgor and softening, with some secondary corrosive dependency related to the pH of a solution.