Old Hospital Samples Became DNA Lifelines in Israel’s Toughest Identification Effort

When disaster strikes on a scale that overwhelms every conventional forensic tool, investigators are forced to rethink where identification evidence can come from. A new study published in the International Journal of Legal Medicine describes exactly such a rethink, born from the aftermath of the October 7, 2023 terrorist attack in Israel, which left more than 1,200 people dead and created one of the most demanding disaster victim identification (DVI) operations ever undertaken. Forensic teams at the Israel Police Division of Identification and Forensic Science, working alongside hospital pathologists, turned to an unexpected reservoir of genetic material: the vast archives of formalin-fixed, paraffin-embedded tissue blocks, cytology slides, diagnostic swabs, and stored blood samples held in Ministry of Health repositories. Their systematic evaluation of 151 archived clinical specimens, some dating back to 2003, now offers a technical roadmap for any country facing a mass fatality event in which entire families perish together.

The core problem the researchers confronted is structural to DVI work itself. Identification by DNA typically relies on comparing post-mortem profiles recovered from remains against ante-mortem references: DNA from a toothbrush, a razor, a hairbrush, or a personal item reliably handled by the missing person. That approach collapses when a catastrophe kills whole families at once, because there is no surviving household from which to gather personal effects, and because direct relatives who would normally donate reference samples may themselves be among the victims. The October 7 massacre produced precisely this scenario across multiple communities, leaving investigators with fragmented, sometimes burned or commingled remains and a shortage of the reference material on which standard kinship matching depends. The solution proposed in the study was to mine medical archives, where every biopsy, Pap smear, surgical specimen, and diagnostic swab represents a documented, dated, and individually attributable sample of a specific patient’s DNA.

The researchers call this strategy a self-direct-reference antemortem DNA database, a term that captures its key advantage: the archived specimen is not a proxy handled by the victim, such as a toothbrush that could carry someone else’s DNA, but the victim’s own biological material collected under clinical conditions and linked to a verified identity through medical records. That distinction matters enormously in forensic practice, where misattribution of a reference sample can derail an entire identification. A paraffin block from a 2015 surgery or a cytology slide from a routine screening test carries an unbroken chain of custody through the pathology laboratory, and the DNA within it belongs, with near certainty, to the named patient. In effect, decades of routine diagnostic medicine had unknowingly been building a national ante-mortem DNA repository, waiting for a method to unlock it.

Unlocking it, however, is far from trivial, and this is where the study makes its most valuable technical contribution. Formalin fixation, the standard preservative for surgical pathology specimens, cross-links proteins and fragments DNA into short pieces, often just a few dozen to a few hundred base pairs long. Paraffin embedding adds further chemical and thermal stress over years of storage. Forensic short tandem repeat (STR) profiling, the workhorse of human identification, normally prefers intact DNA and amplifies loci that can span several hundred base pairs, so degraded archival DNA poses a real risk of allele dropout, locus amplification failure, and partial profiles. The team therefore designed a controlled optimization experiment, treating the archived specimens not as a last resort but as a material class with its own processing requirements, to be characterized systematically rather than improvised case by case.

The experimental design was straightforward but rigorous. The 151 specimens fell into three categories: 131 histological samples in the form of FFPE tissue blocks and cytology slides, 8 diagnostic swabs, and 12 blood or serum samples, all collected between 2003 and 2023. The investigators varied four parameters and measured their effect on profiling success: the tissue source of the specimen, the DNA extraction method applied, the incubation protocol used during extraction, and the age of the sample. Extracted DNA was amplified with the Investigator 24plex STR kit, and success was quantified as the number of informative autosomal STR loci recovered, with a maximum of 21 usable loci defining a fully informative profile. Descriptive statistics and non-parametric inferential tests were then applied to determine whether differences in outcomes across sample types and methods were statistically significant, which they were, confirming that processing choices genuinely matter rather than being matters of laboratory preference.

The headline result is a range of success rates spanning 67 to 100 percent of mean locus recovery, depending on tissue type and processing optimization. In practical terms, even the worst-performing specimen categories yielded profiles informative enough to contribute to identification, while the best categories performed as reliably as fresh reference material. Blood and serum samples, being less chemically assaulted than formalin-fixed tissue, sat at the favorable end of the range, as did certain tissue types within the FFPE group. The finding that sample age alone did not doom a specimen is particularly striking: blocks two decades old could still yield usable profiles when the right extraction chemistry and incubation conditions were applied. For DVI planners, this transforms the mental model of a pathology archive from a static library of diagnostic slides into a dynamic genetic resource whose yield can be predicted and maximized.

The optimization variables identified by the study carry direct operational significance. Extraction method selection determines how efficiently cross-linked, fragmented DNA is released from fixed tissue, and the literature on FFPE-derived DNA for next-generation sequencing has long shown that different extraction chemistries produce markedly different yields and fragment length distributions. The study extends that insight into the forensic STR context, where the goal is not sequencing read depth but the recovery of a sufficient number of complete, correctly sized STR amplicons. Incubation protocols, including the temperature and duration of the digestion step, similarly influence whether the fragile archival DNA is liberated intact or further sheared. By testing these variables across a real, diverse specimen collection rather than a small proof-of-concept set, the researchers produced guidance that a forensic laboratory can adopt directly, choosing the optimal workflow for each specimen type before committing irreplaceable archive material.

Beyond the immediate Israeli context, the study’s implications reach into global DVI preparedness. International guidelines, including INTERPOL’s DVI framework, emphasize ante-mortem data collection as the bottleneck of every mass fatality response, and historical operations from the Brussels Airport attack to the decades-long Korean War Identification Project illustrate how reference scarcity prolongs identifications and deepens families’ anguish. The Israeli experience adds a new layer to that body of knowledge: national health systems worldwide hold enormous, already-identified biological archives, and the study demonstrates that these archives can be converted into ante-mortem DNA references with predictable, optimizable success rates. The authors frame their findings as actionable guidance for DVI preparedness, and the phrase is apt, because the practical lesson is that countries need not wait for a catastrophe to begin cataloging, validating, and integrating their medical specimen repositories into forensic contingency planning.

There are also important scientific and ethical dimensions that the study implicitly raises. Forensic genetics in Israel operates within a legal and cultural landscape in which religious considerations, including Jewish law’s sensitivities around the treatment of human remains and autopsies, shape identification practice, making DNA-based methods that minimize invasive procedures especially valuable. The use of archived clinical specimens for identification purposes sits at the intersection of medical confidentiality, data protection, and forensic necessity, and the involvement of hospital pathology institutes alongside police forensic scientists in this study reflects the kind of institutional partnership such an approach requires. The authors report no competing interests and no external funding, and the work emerged from operational necessity rather than a pre-planned research program, which lends it the credibility of methods forged under real casework pressure.

What makes this research resonate beyond forensic circles is the way it reframes ordinary medical infrastructure as a form of civil resilience. Every pathology laboratory in the world quietly preserves a record of the people it has served, in the form of tissue blocks and slides that are retained for years or decades for clinical and legal reasons. The October 7 massacre forced Israeli scientists to recognize that this record could serve the dead and their surviving relatives when every other avenue of identification had been exhausted. The study’s systematic demonstration that 67 to 100 percent of informative STR loci can be recovered from such material, given the right extraction and amplification choices, converts a desperate improvisation into a reproducible protocol. For the families of the victims, the science delivered something no other method could: certainty about the fate of loved ones. For the global forensic community, it delivers a tested blueprint for the next inevitable mass disaster, one that begins not in the morgue but in the quiet shelves of the hospital archive.

Subject of Research: Use of archived medical specimens as ante-mortem DNA references for disaster victim identification

Article Title: Archived medical specimens as antemortem DNA references for disaster victim identification, optimization study following the October 7 massacre

Article References: Ido, A., Avrahami, K., Feinberg, T., Itzhaki-Alfia, A., & Herman, Y. (2026). Archived medical specimens as antemortem DNA references for disaster victim identification, optimization study following the October 7 massacre. International Journal of Legal Medicine. https://doi.org/10.1007/s00414-026-04028-0

Image Credits: AI Generated

DOI: 10.1007/s00414-026-04028-0

Keywords: disaster victim identification, ante-mortem DNA, FFPE specimens, STR profiling, forensic genetics, mass casualty, October 7 attack, pathology archives, DNA extraction, International Journal of Legal Medicine, Israel Police, DVI preparedness