Prosecuting Cold Cases Using DNA: Strategy, Labs, Funding

Cold cases test the patience and promise District Attorney's offices make to victims. DA teams face aging evidence, faded memories, high public interest, and budgets that make progress hard. Yet the path forward is clear. Modern DNA methods give prosecutors new leads and new confidence in court. With the right strategy, partners, and funding, DA offices can move stalled cases and deliver justice.

In this guide, we share how prosecutors approach prosecuting cold cases using DNA, from lab choices to trial strategy, with a clear focus on ethics and survivors, and how ERI Grants supports that work.

The Modern DNA Toolkit For Cold Cases

Prosecuting cold cases using DNA starts with a realistic inventory of what prosecutors have and what they can test. DA offices assess sample type, age, storage history, and case questions, then pair that with lab capacity and jurisdictional policies.

Core Methods: STRs, Y-STRs, mtDNA, And Touch DNA

Prosecutors start with STR testing for standard comparisons and database searches. When male signal is low or mixed, they use Y-STRs to focus on paternal lines. For hair shafts and old bones, mtDNA can help trace maternal lines and exclude or include families. DA teams also consider touch DNA from handled items, using clean collection, careful cutting, and lab protocols that guard against transfer.

Forensic Genetic Genealogy And CODIS: When And How To Use Each

Prosecutors run CODIS when they have a probative profile. They use forensic genetic genealogy when CODIS gives no lead or when the suspect is unknown and likely outside offender databases. DA offices start with policy reviews and legal approvals, limit genealogy searches to allowed databases and case scope, create an investigative lead, then confirm identity with a direct reference or abandoned DNA and a standard STR profile.

Interpreting Complex Mixtures And Low-Template Samples

Cold case samples are often degraded and mixed. Prosecutors use probabilistic genotyping with clear lab documentation. They ask labs for sensitivity studies, stutter policies, and thresholds that match their validation. DA teams request clear explanations of assumptions and keep interpretations simple and tied to case facts so a jury can follow.

Building A Prosecutable Case From Old Evidence

The goal for DA offices is a clean, admissible record that a jury understands. Prosecutors combine DNA results with corroboration and sound charging decisions.

Evidence Retrieval, Preservation, And Chain Of Custody

Prosecutors map the path of every item from scene to storage to retesting. They record who handled it, how it was packaged, and how it was stored. DA teams fix gaps where they can with testimony and records, repackage items with fresh seals and labels, and use current storage standards to protect any remaining sample for defense testing.

Corroboration Beyond DNA: Linking The Suspect To The Crime

DNA can place a person near an item, but context matters. Prosecutors seek timelines, alibi checks, witness statements, phone records, and location data. They compare injury patterns, entry points, and known habits. DA offices look for past contacts between victim and suspect, and for motive or opportunity. They build a narrative that explains how the DNA fits the crime, not a narrative that rests on DNA alone.

Charging Decisions, Statutes Of Limitations, And Case Selection

Prosecutors confirm the statute of limitations. Many violent crimes have no time bar, but DA offices verify the law at the time of the offense. They select charges that match the strongest proof and the best jury story, consider evidentiary risks, expected defense themes, and sentencing outcomes. They choose cases with testable DNA, a path to corroboration, and clear community impact.

Coordination and Collaboration

Cold case success depends on coordination. Prosecutors plan early with investigators, lab leaders, and medical examiners, and they set clear roles and timelines.

DA offices rank cases by DNA presence, sample quality, and solvability factors. They schedule testing in phases so early results inform next steps. Prosecutors meet with lab staff to set expectations and reporting formats and align budget and grant plans so testing does not stall.

District Attorney's offices also look for outside funding to support DNA testing and victim services. The Educational Research Institute partners with DA offices to manage pre-award applications, budgets, and reporting, essentially taking the administrative burden off prosecution teams so they can focus on building strong cases.

If your office needs help, ERI Grants can assist with grant writing, bid proposals, evaluations, and training. Learn more about our mission and meet the experienced team that supports prosecutors nationwide. To understand how we structure our support, review our transparent fee structure.

Funding Spotlight: Prosecuting Cold Cases Using DNA Program

Moving a cold case from storage to resolution requires resources, time, and persistence. The Prosecuting Cold Cases Using DNA Program from the Bureau of Justice Assistance offers a way for agencies to turn scientific breakthroughs into court ready cases. This federal program supports violent cold case prosecution when a suspect DNA profile already exists.

Funding can strengthen case review, expand forensic testing, support investigative momentum, and prepare teams for trial. Awards can reach up to 500,000 dollars, giving offices the ability to pursue the truth with urgency and care. The program focuses on cases that are ready for action and does not fund the creation of new cold case units.

Agencies looking to plan ahead benefit from staying informed on BJA updates. Some offices also explore additional opportunities like the Emmett Till Cold Case Investigations and Prosecution Program, which focuses on racially motivated crimes with historical elements.

ERI Grants works with District Attorney offices that are prepared to advance this work. To understand how our support is structured with transparency and fairness, you can review our fee approach. When you are ready to take the next step, our team will help turn goals into funded, compliant, and sustainable initiatives.

Conclusion

Prosecuting cold cases using DNA demands science, planning, and care for people. DA offices build cases with solid lab work, clean chains, and clear stories. They protect rights and privacy at every step. They prepare experts who teach, and they seek funding that keeps testing and services moving. If your office is ready to move a stalled file, ERI Grants can help you plan the lab work, the legal path, and the support your survivors deserve. Contact us today to discuss how we can support your cold case initiatives.

Frequently Asked Questions

What does prosecuting cold cases using DNA involve?

Prosecuting cold cases using DNA starts with auditing evidence, selecting suitable tests (STRs, Y-STRs, mtDNA, touch DNA), and aligning with lab capacity and policy. Prosecution teams document chain of custody, use probabilistic genotyping for mixtures, and pair DNA with corroboration—timelines, witnesses, and records—to build a clear, admissible narrative for jurors.

When should investigators use forensic genetic genealogy instead of CODIS?

Run CODIS when you have a probative STR profile that might match offender databases. Use forensic genetic genealogy when CODIS yields no lead or the suspect likely isn't in offender files. Limit searches to permitted databases, get legal approvals, develop an investigative lead, and confirm with a direct reference STR profile.

How do prosecutors explain DNA statistics to juries effectively?

Prosecutors match the lab's statistic to a simple, case-tied lesson. They clarify the difference between random match probability and likelihood ratios, avoid jargon, state contributor count, and link the statistic to key items. They use clean visuals and emphasize what the number does—and doesn't—say about guilt in this case.

Do statutes of limitations affect prosecuting cold cases using DNA?

Yes. Many violent crimes have no statute of limitations, but prosecutors verify the law as it existed at the time of the offense. They select charges that fit the strongest proof, weigh evidentiary risks and sentencing, and prioritize cases with testable DNA, corroboration paths, and clear community impact.

How long do cold case DNA investigations take, and what do they cost?

Timelines vary widely—from months to several years—depending on evidence condition, lab backlogs, genealogy steps, and legal processes. Costs range from standard STR testing (hundreds to low thousands) to advanced methods and genealogy (several thousand to tens of thousands). Grants and phased testing plans can control budgets and keep work moving.

Is forensic genetic genealogy evidence admissible in court?

Admissibility depends on jurisdiction and proper procedures. Courts look for validated lab methods, clear documentation, compliance with database terms, and probable-cause steps like warrants for reference samples. Genealogy typically generates leads; identity must be confirmed with standard STR profiling before trial to meet evidentiary standards when prosecuting cold cases using DNA.