New and Emerging Trends in Cold-Case Homicide Investigations

“Agencies that build adaptable systems today will be the ones that consistently generate new leads, surface hidden connections, and deliver long-delayed justice.”

The investigation of “cold-case” homicides is quietly undergoing a transformation — one that promises to reshape what justice looks like for families who have waited years, sometimes decades, for answers. Advances once considered experimental are now becoming routine tools, and long-dormant evidence is offering new possibilities for movement, clarity, and closure. What’s emerging is not just a more technologically capable approach to cold cases, but a more disciplined, systematic, and hopeful era in which agencies can revisit the past with sharper tools, better frameworks, and a clearer path to resolution.

This highly specialized focus of policing work is experiencing its biggest change since the introduction of CODIS. While the essential methods, such as thorough case review, re-engaging witnesses, and careful evidence management, remain a staple of good investigative methodology, several new developments are changing how agencies find leads, verify identities, and build cases for prosecution. These include:

1) Investigative Genetic Genealogy (IGG) moves from novelty to governed practice

Since the U.S. Department of Justice issued its Interim Policy on Forensic Genetic Genealogy (2019), agencies now have clearer guidelines for when and how to use IGG, typically after traditional methods are exhausted, with proper databases and oversight. That policy presents IGG as a lead-generation tool, not a source of courtroom-ready identity on its own, aiding detectives in integrating genealogical research with conventional investigation. Some states have added legal restrictions: in 2021, Maryland and Montana became the first to require judicial approval to search consumer DNA databases, indicating a maturing legal environment that balances public safety with genetic privacy.

2) Better recovery of “old” or low-template DNA — especially from porous or rough surfaces

A major limitation of legacy evidence is that prior swabbing or cutting often failed to collect enough DNA. Wet-vacuum sampling (e.g., the M-Vac method) has demonstrated significant improvements on challenging surfaces found in homicide cases, such as clothing, concrete, and wood. Peer-reviewed studies and federal lab research indicate that wet-vacuum methods can recover considerably more nuclear DNA than wet-swabbing on many porous materials, often making the difference between getting "no profile” and a usable one for STR or SNP analysis. These enhancements directly increase the potential of evidence from the 1980s to 2000s to yield results when retested today.

3) Ballistics intelligence is linking more shootings and surfacing suspects across cases

The National Integrated Ballistic Information Network (NIBIN) is expanding, with ATF emphasizing its role in linking cartridge cases and crime guns across different jurisdictions. Crime Gun Intelligence Centers (CGICs) combine NIBIN correlations with quick investigative actions, video analysis, and eTrace to turn technical clues into arrests. For cold homicides, especially those involving firearm evidence but limited eyewitness cooperation, these networks now often reveal connections between cases that weren’t possible a decade ago.

4) Institutional reforms: dedicated cold-case units, standardized solvability reviews, & NamUs support

With approximately 250,000 unresolved murders nationwide, agencies are responding by establishing specialized units, implementing structured case triage, and staffing teams with experts such as analysts, genealogists, and victim advocates. Best-practice guidance highlights the importance of standardized solvability assessments and case management strategies to prioritize retestable evidence and actionable leads. At the national level, NamUs has established a Cold Case Advisory Team to support agencies in reviewing their cases and ensuring that all forensic options, including DNA, genetic genealogy, anthropology, and odontology, are thoroughly explored.

5) Expanded forensic pathways for unidentified decedents and victim-centered approaches

NIJ and partner labs are developing methods to identify difficult skeletal remains and improve kinship inference, work that now often aligns with IGG to give names to unidentified homicide victims. This victim-focused approach (notifications, advocacy, trauma-informed communication) is becoming more common in cold-case policies, enhancing public trust and cooperation when detectives reopen long-unsolved crimes.

6) Smarter re-submission and digital re-examination

Even without new technology, fresh laboratory thresholds, probabilistic genotyping, and modern contamination controls can generate profiles from items previously reported as “no result.” On the digital side, renewed reviews often combine call-detail records, historical cell-site data, and current video workflows with modern analytics, as well as OSINT (Open-Source Intelligence), to locate witnesses, associates, or online disclosures that didn’t exist at the time of the offense. Practitioner guidance increasingly recommends routine re-submission and comprehensive reanalysis during solvability review cycles.

Implications for practice

The common thread across these trends is a disciplined, futures-ready approach: a methodical cold-case review, early engagement with forensic partners, and pre-planned legal and ethical frameworks for IGG and digital searches. Agencies that formalize these elements — unit staffing, triage criteria, lab liaisons, integrated analytics, and victim-centered services — are best positioned to turn new science into courtroom-ready evidence. But more importantly, these practices signal a shift toward a sustained, anticipatory mindset in cold-case work.

As forensic tools continue to evolve and digital information grows more accessible, the agencies that build adaptable systems today will be the ones that consistently generate new leads, surface hidden connections, and deliver long-delayed justice. In this evolving environment, cold-case investigation becomes not just a retrospective effort, but a strategic, forward-leaning commitment to solving the most serious crimes with the best methods available — and those still to come.

Selected Sources (open access or official)

• U.S. Department of Justice. Interim Policy on Forensic Genetic Genealogy (Sept. 24, 2019).Department of Justice+1

• Electronic Frontier Foundation. “Maryland and Montana Pass the Nation’s First Laws Restricting Law Enforcement Access to Consumer DNA Databases” (June 7, 2021).Electronic Frontier Foundation

• University of Chicago Law Review Online. Geary, L. “A Critical Eye Toward Commercial DNA Database Criminal Procedures” (discussing state statutes).The University of Chicago Law Review

• Journal of Forensic Sciences (open-access on PMC). McLamb, J.M., et al. “Comparison of the M-Vac Wet-Vacuum-Based Method and the Wet-Swabbing Method for DNA Collection on Various Substrates” (2020).PMC

• ATF. “National Integrated Ballistic Information Network (NIBIN) – Fact Sheet” and recent technical report examples.ATF+1

• Joyce Foundation. Optimizing Crime Gun Intelligence (July 2024).assets.joycefdn.org

• Council on Criminal Justice / PERF commentary: Scaling cold-case capacity and solvability assessments (Jan. 2025).National Policing Institute

• NIJ. “Cold Case Investigations: National Best Practices for Implementing and Sustaining a Cold Case Investigation Unit” and NamUs Cold Case Advisory Team (2024).National Institute of Justice

About the author

Frank Tona is a lieutenant with the Charles County Sheriff's Office, MD. Cold case expert, author, adjunct professor. To read his full bio click here.