# Proteomics in Forensic Analysis: Applications for Human Samples
## 4 Challenges, Considerations, and Future of Forensic Proteomics
One of the appropriate estimations of error rates in proteomics is the false discovery rate (FDR). Thus, to be admissible in court, proteomics methods must undergo extensive method validation. New methods must be published for repetition by other groups and the acceptance of the scientific community [24]. Proteomics is considered an interdisciplinary science because it depends on the development of analytical chemistry (peptide/protein identification and quantification), physical chemistry (sample separation), electrical engineering (mass spectrometry design), statistics, and bioinformatics (data analysis) [1; 2]. The development and applications of proteomics have emerged as powerful tools in forensic science. Proteomics has attracted forensic scientists in recent years owing to its applicability to answer different forensic questions [4; 11]. It can provide informative data that cannot be answered by DNA analysis. Although it is in its early stages, forensic proteomics will definitely continue to be studied and evaluated for applications in forensic contexts. Currently, forensic proteomics is developed for several applications, including human identification, PMI estimation, and identification of body fluids or tissues from unknown samples. Proteomic analysis of hair for human identification has been shown to be effective and robust [18; 141]. Further studies will be conducted to validate the methods with a larger number of samples. Bone and some other samples (e.g., muscle, brain, cerebrospinal fluid, and decomposition fluid) can be used for the estimation of PMI. Among them, bone has been widely used, and a large number of protein biomarkers have been found [29]. Forensic proteomic studies of bone will be further carried out to identify new biomarkers and validate them. In addition, bone can be effective in estimating age-at-death via some protein biomarkers, such as AHSG [41]. Finally, the identification of body fluid (including their trace trapped in fingernail and on fingermark) can be accomplished using the Van Steendam decision tree based on protein biomarkers of each fluid type [14]. More protein biomarkers will be continuously found to improve the identification workflow. In the case of body tissues, proteomic studies will focus on the identification of protein biomarkers for each tissue prior to applying them to distinguish tissue types [12]. As a new member of the forensic science family, proteomics requires considerable development time to be widely applied in this new field. In addition, efforts should be made to combine it with other well-established tools of forensic science. Conceptualization, V.-A.D., J.-M.P., H.-J.L. and H.L. ; writing--original draft preparation, V.-A.D. and J.-M.P. ; writing--review and editing, H.-J.L. and H.L. ; visualization, V.-A.D.; project administration, J.-M.P. ; funding acquisition, H.L. All authors have read and agreed to the published version of the manuscript. This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. NRF-2017M3D9A1073784, NRF- 2020R1I1A1A01074257). **Institutional Review Board Statement:** Not applicable. Figure 7: The forensic method development process. Reprinted with permission from [178]. Copyright (2019) American Chemical Society.