In forensic genetics, the identification of an individual is often carried out by comparing unknown DNA profiles obtained in a case against databases or references. When no match is found, investigators need new tools in order to obtain additional leads. The latest technical advances now make it possible to predict externally visible characteristics. With this objective, predicting the age of an individual through DNA methylation analysis remains one of the last challenges. The prediction models have to account for the specific constraints of this field, including tissue specificity and DNA availability (i.e., low DNA amounts or low-quality DNA). Jung and colleagues have recently produced models from blood, saliva and buccal cells by using a single base extension sequencing method. With the goal of evaluating these models in our own analytical conditions, saliva and buccal cell samples from 115 French individuals between the ages of 0 and 88 years old were collected and analyzed. After having determined the optimal analysis conditions, including the DNA quantity for bisulfite conversion (75 ng), some differences were highlighted in the measured methylation rates between the two studies. Despite these discrepancies, the prediction performance levels remain very similar, our study showing mean absolute errors of 3.5 years, 3.9 years and 3.2 years, respectively, for the saliva, buccal swab and multitissue model, with limitations observed for the oldest and youngest individuals. Furthermore, we propose the use of a prediction interval with an error dispersion and correct prediction rate at ±5 years and ±10 years, respectively.

The IRCGN (Institut de Recherche Criminelle de la Gendarmerie Nationale) is a forensic science institute built by the French Gendarmerie which has the ability to exploit crime scene evidence. Any piece of evidence, anywhere in the world, in any environment, can be examined by IRCGN teams deployed in just a few hours. During the past 10 years, experts specializing in genetics have developed innovative genetic engineering technologies for application in forensic sciences. In this review, we highlight the main innovations and the creation of new tools for human identification, which are fully suited to the French Gendarmerie’s needs. Devices developed by the IRCGN are specific to the Gendarmerie’s purposes.

Forensic genetic analysis of biological traces collected at a crime scene can aid in the rapid identification of perpetrators. Touch DNA samples consist of invisible biological traces left on an object or person after skin contact. Although these samples represent a significant portion of DNA evidence, they often fail to yield usable DNA profiles due to challenges in detection and collection. A decision-support tool capable of highlighting such traces would optimize sampling strategies and improve forensic outcomes. We previously identified cell-derived markers that persist on shed corneocytes. Here, we propose an in situ cytochemistry-based tool using a dual labeling technique that combines chromogenic and fluorescent visualization to enhance the detection of otherwise invisible traces. Chromogenic labeling of cell-derived mannose residues and keratin 10 allows the visualization of up to 100 cells on surfaces and swabs and enables the acquisition of usable DNA profiles. A combination of FITC-conjugated primary probes and an HRP-conjugated anti-FITC antibody enables versatile visualization, allowing both chromogenic and fluorescent detection of otherwise invisible biological traces and offering adaptability across various substrates. Corneocytes from fingermarks were successfully detected on both light and opaque surfaces (ceramic and metal) using a single cytochemistry process. In addition, the presence of biological material after swabbing a fingermark was highlighted, notably by chromogenic labeling. This approach could improve on-field touch DNA sample detection, proving valuable both before and after sampling. It can highlight areas for collection or prioritize swabs likely to contain biological material, thereby increasing the chances of obtaining usable DNA profiles for criminal investigation.

Background/Objectives: The expansion of direct-to-consumer (DTC) genetic testing has generated civilian genomic databases containing tens of millions of profiles, some of which may be available, under specific conditions, for criminal investigations. Meanwhile, artificial intelligence (AI) is reshaping forensic genetics through applications such as kinship inference, DNA mixture deconvolution, probabilistic phenotyping, and the prioritization of investigative leads. This review examines the scientific, legal, and ethical implications of the convergence between DTC genetic databases, forensic investigative genetic genealogy (FIGG), and AI-assisted forensic analysis. Methods: This article presents a multidisciplinary narrative review at the intersection of forensic genomics, FIGG, artificial intelligence, genomic data governance, and bioethics, with particular attention to French, European, and international regulatory frameworks. Results: Six major dimensions structure the field: (i) the current state of forensic genomic technologies, including STRs, SNPs, and next-generation sequencing; (ii) the contribution of AI to forensic genetics and FIGG; (iii) the governance of large-scale genomic data; (iv) regulatory fragmentation across jurisdictions; (v) the principal bioethical tensions raised by the forensic use of DTC genetic databases; and (vi) future governance needs and operational recommendations. Across these dimensions, three findings emerge. First, genealogical matches and AI-supported outputs should be understood primarily as investigative leads rather than autonomous judicial evidence. Second, the relational nature of genomic data exposes non-consenting relatives to potential forensic scrutiny, thereby challenging traditional models of individual consent and privacy. Third, the absence of harmonized standards for validation, transparency, and oversight remains a major obstacle to legal certainty, judicial admissibility, and public legitimacy. Conclusions: The forensic use of DTC genetic databases should not be understood as a purely technical extension of conventional DNA profiling. It reflects a broader transformation in the relationship between genomic knowledge, criminal investigation, and fundamental rights. Its long-term legitimacy and operational viability will depend on the combined strength of scientific reliability, legal proportionality, ethical safeguards, and meaningful democratic oversight.

Background: The success of forensic genetics has led to considerable numbers of DNA samples that must be stored. For example, the genetic casework unit of the forensic institute of the French gendarmerie analyzes more than 70,000 casework samples per year mainly from swabs that are fully consumed during DNA extraction. The only way to process further analyses is to preserve DNA. Currently, the most common technique used for the long-term preservation of DNA is to freeze the extracted DNA at −20 °C or −80 °C. However, this preservation method involves significant constraints (large equipment), risks (equipment failure), and is not ecologically sustainable due to its high energy consumption. Many solutions for DNA preservation at room temperature exist based either on fibrous supports or on anhydrobiosis. However, few studies have examined the efficiency of these systems in preserving very-low DNA amounts, such as those in forensic samples (≤1 ng), while ensuring full recovery and the ability to retest the samples many years later. Methods: We choose to evaluate the ability of the anhydrobiosis technology from GenTegra^® LLC to preserve DNA extracts from one month to one accelerated year from different DNA quantities (from 1 ng to 0.2 ng) and sources (NIST, mocked samples, and true casework mixtures). We studied the quantity, integrity of DNA, and also the quality of the STR genetic profiles obtained. Results and Conclusions: Our results prove the high potential of this technology to preserve and to allow an effective recovery of the DNA extracts for forensic purposes.