Age characterization of donor based on fatty acid substances analysis in fingermarks

As a critical frontier in forensic science, the profiling of physical evidence characteristics has garnered substantial attention. This study employed gas chromatography-mass spectrometry (GC-MS) to investigate age-related differences in sebaceous fingermark fatty acid compositions. Fingermark samples from 80 volunteers were analyzed to characterize fatty acid profiles across different age groups. Non-parametric tests were used to identify target fatty acids with significant age-dependent variations, followed by comparative evaluation of unsupervised (PCA) and supervised (RBF, MLP) classification models to develop a high-accuracy age prediction framework. Results revealed distinct fatty acid trends with age: younger donors predominantly exhibited saturated fatty acids with carbon numbers ≤ 10; mid-chain saturated fatty acids (C10-C20) showed minimal age-related variation; and long-chain fatty acids (C ≥ 20) were more abundant in older donors. Significant age-group differences were identified for octanoic acid, decanoic acid, palmitoleic acid, palmitic acid, oleic acid, stearic acid, behenic acid, and tetracosanoic acid. The multi-layer perceptron (MLP) model achieved an overall accuracy of 84.6 %, outperforming other algorithms in age classification. This study enhances the understanding of age-related lipid dynamics in sebaceous fingermarks and establishes a robust analytical pipeline for forensic age profiling, offering practical implications for criminal investigation and biometric identification.