Department of Forensic Pathology, Xi'an Jiaotong University, Xi'an, 710061, China.
Shanghai Key Laboratory of Forensic Medicine, Shanghai Forensic Service Platform, Academy of Forensic Science, Shanghai, 200063, China.
Int J Legal Med. 2021 Jan;135(1):73-80. doi: 10.1007/s00414-020-02367-0. Epub 2020 Jul 10.
Semen stains are the most important biological evidence when identifying the aggressor in sexual assault cases. Current detecting assays of semen stains species identification were not confirmative enough. In this study, we investigated the potential of species identification of semen stains by using attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy combined with advanced chemometrics methods. The effect of substrates types and time since deposition (TSD) were considered in the study. A partial least squares-discriminant analysis (PLS-DA) classification model was established which demonstrated complete separation between human and other species (rabbit, dog, boar, bull, and ram). Validation was conducted which showed prediction abilities with 100% accuracy. Additionally, we found species identification could be achieved without sperm cells which proved ability of spectroscopic methods detecting the semen samples from the case of azoospermia. This work provides a powerful and practical tool for species identification of semen stains in real forensic casework.
精液斑痕是鉴定性侵犯案件中施害者最重要的生物证据。目前，精液斑痕种属鉴定的检测方法还不够确定。在本研究中，我们通过使用衰减全反射（ATR）傅里叶变换红外（FTIR）光谱结合先进的化学计量学方法来研究精液斑痕种属鉴定的可能性。本研究考虑了基质类型和沉积时间（TSD）的影响。建立了偏最小二乘判别分析（PLS-DA）分类模型，该模型能够完全区分人类和其他物种（兔、狗、猪、公牛和公羊）。验证结果表明，预测准确率达到 100%。此外，我们发现无需精子细胞即可进行种属鉴定，这证明了光谱方法能够从无精症案例中检测精液样本的能力。这项工作为实际法医学案例中精液斑痕的种属鉴定提供了一种强大而实用的工具。
