Forensic DNA Evidence Backlog: Legal Impact and Federal Fixes

A forensic DNA evidence backlog builds whenever crime laboratories receive biological samples faster than their analysts can process them, and under the National Institute of Justice’s definition, a case is already backlogged once it has waited 30 days after submission.¹ In practice, many samples wait far longer than a month. Congress has authorized $151 million per year through fiscal year 2029 to shrink those queues, yet the gap between evidence collection and courtroom-ready results persists, with real costs to investigations, to defendants, and to victims waiting for answers.²

Two Different Backlogs, One National Database

Forensic professionals separate the problem into two queues. Casework backlogs are the untested biological samples collected from crime scenes: blood, saliva, skin cells, hair. Database backlogs are reference samples taken from convicted offenders or arrestees that have not yet been processed and uploaded into the FBI’s Combined DNA Index System, known as CODIS.³

The split matters because each queue blocks a different kind of match. An unanalyzed crime-scene sample means a suspect’s profile never gets searched. An unanalyzed offender sample means that person’s profile is missing when CODIS searches run against unsolved cases. The system only works when both sides are complete. As of November 2025, CODIS held more than 19.2 million offender profiles and had produced over 781,000 hits aiding roughly 758,000 investigations.⁴ Every sample sitting in a backlog is a potential match the database cannot see.

Why the Queue Keeps Growing

More money alone has not fixed this, because the inputs to the system keep expanding faster than lab capacity.

More Evidence Per Scene

Modern forensics can pull usable profiles from “touch DNA,” the microscopic skin cells left when someone handles an object. A generation ago, investigators needed a visible stain. Now a doorknob, a steering wheel, or a zipper pull is worth swabbing. The number of items worth testing at any given scene has grown sharply, and each swab is another sample in the queue.

Collection laws have expanded in parallel. Many jurisdictions now require DNA collection at booking for a broader list of offenses, so more arrests generate more reference samples. More items per scene plus more arrests per month equals volume growth that would strain even a well-funded lab.

Staffing and Equipment

DNA analysts take time to train. FBI quality assurance standards require a minimum of six months of human DNA laboratory experience, including at least three months in a forensic or database DNA lab, before an analyst can work independently.⁵ Vacancies cannot be filled on short notice, and government labs lose trained analysts to private employers. The median annual wage for forensic science technicians was $67,440 as of May 2024.⁶ When a public lab cannot match private-sector offers, positions stay open for months.

Equipment compounds the staffing problem. High-throughput instruments that run dozens of samples at once are expensive to buy and maintain, and many public labs are still running machines that were state-of-the-art a decade ago. Short-staffed, under-equipped labs produce a self-reinforcing cycle: existing analysts burn out, turnover climbs, and the queue lengthens.

The Sexual Assault Kit Problem

A large share of the national backlog sits inside one specific category: untested sexual assault kits. A 2021 study drawing on data from more than 900 counties estimated that between 300,000 and 400,000 kits went unsubmitted to laboratories between 2014 and 2018. A separate 2018 study funded by the National Institute of Justice estimated that roughly 200,000 untested kits remained in police custody.⁷

The scale drove Congress to attach conditions through the SAFER Act. Laboratories receiving federal backlog-reduction funds must now audit the sexual assault kits in their possession, estimate how many remain untested, complete the audit within one year of receiving the grant, and report to the Department of Justice every 60 days on how those samples are being processed.⁷ A separate federal Sexual Assault Kit Initiative gives competitive grants specifically for inventorying, testing, and investigating cases tied to unsubmitted kits.

When the kits are tested, the yield is significant. Research cited by Congress indicates that 25 to 50 percent of tested kits generate CODIS-eligible DNA profiles, and 50 to 60 percent of those profiles produce a hit identifying a suspect.

What the Delay Does Legally

Testing delay is not just a scheduling problem. It changes what prosecutors, defendants, and prisoners can do.

The Statute of Limitations Can Restart

Federal law anticipates that DNA may identify a suspect long after the normal filing deadline. Under 18 U.S.C. § 3297, when DNA testing implicates an identified person in a federal felony, the prosecution gets an additional period equal to the original limitation period, running from the date the DNA results pointed to that person.⁸ Without that provision, suspects identified through belated testing could escape prosecution entirely.

Speedy Trial Pressure

For defendants already charged, the federal Speedy Trial Act generally requires trial to begin within 70 days of indictment or the defendant’s first court appearance, whichever is later. The statute contains no explicit carve-out for forensic laboratory delays. Judges can grant continuances when the “ends of justice” outweigh the defendant’s interest in a speedy trial, and case complexity may qualify, but a continuance cannot be granted on the basis of general court congestion or the government’s lack of preparation.⁹ Prosecutors leaning on that exception to cover backlog delays face real scrutiny.

Evidence Can Degrade

The longer biological evidence waits, the greater the risk that it becomes unusable. Dried samples require humidity-controlled storage, and improper conditions can degrade DNA to the point that no profile can be developed.¹⁰ A lab holding two years of casework must also keep those samples viable for two years, and overburdened facilities often struggle to do so. A processing delay then becomes a permanent loss.

People Already in Prison

Backlogs also reach into post-conviction cases. Federal inmates asserting innocence can petition for DNA testing under 18 U.S.C. § 3600. The applicant must assert actual innocence under penalty of perjury, identify evidence that was never tested or could be retested with newer technology, and show that the proposed testing could produce results raising a reasonable probability that the applicant did not commit the offense.¹¹ Even when a court orders the testing, the sample enters the same queue as every other case, and the applicant remains incarcerated during the wait.

To help states absorb these costs, Congress created the Kirk Bloodsworth Post-Conviction DNA Testing Grant Program, named after the first death-row inmate exonerated by DNA. The program is codified at 34 U.S.C. § 40727 and has authorized $10 million per year in state grants.¹²

The Federal Programs Attacking the Backlog

The primary federal response is the Debbie Smith DNA Backlog Grant Program at 34 U.S.C. § 40701. Congress has authorized $151 million per year for fiscal years 2024 through 2029 for grants to state and local forensic laboratories.² That authorization is a ceiling rather than a guarantee. Full-year appropriations for fiscal year 2026 have not yet been enacted, and the program’s funding status for that year remains uncertain.¹³

Grants under the statute can be used for three purposes: analyzing crime-scene DNA for inclusion in CODIS, processing offender and arrestee samples for the database, and increasing overall laboratory capacity. The law requires prioritizing sexual assault evidence when crime-scene analysis funds are allocated, and up to one percent of total grant funding may go to laboratory accreditation, external audits, and auditor training.² In practice, labs use the money to hire analysts, buy automated workstations, pay overtime, upgrade data systems, and outsource overflow cases to private labs. Funds cannot be diverted to general law enforcement operations.

Quality Assurance Standards

Under 34 U.S.C. § 12591, the FBI Director must issue quality assurance standards for forensic laboratories conducting DNA analyses, including proficiency testing. An advisory board of scientists from government, academic, and private forensic labs develops the recommended standards, and the Director adopts them with any appropriate revisions.¹⁴ Labs that participate in CODIS must comply with those standards, and grant applicants typically must hold ISO/IEC 17025 accreditation.

Rapid DNA at Booking

A newer piece of the strategy is Rapid DNA, fully automated instruments that can generate a profile from a mouth swab in one to two hours without a traditional lab or human interpretation.¹⁵ The Rapid DNA Act of 2017 authorized the FBI Director to set standards for these instruments and allowed qualifying profiles generated at booking stations to be uploaded directly into CODIS.¹⁶

The idea is to treat DNA at booking the way law enforcement already treats fingerprints: identify arrestees on site and search their profiles within hours instead of weeks. By handling routine reference samples at the booking station, Rapid DNA frees trained analysts to focus on complex crime-scene casework that still requires expert interpretation. It is not a substitute for full forensic analysis of crime-scene evidence, but it removes one of the highest-volume contributors to database backlogs.

1
Office of Justice Programs. The DNA Backlog
2
Office of the Law Revision Counsel. 34 USC 40701 – The Debbie Smith DNA Backlog Grant Program
3
National Institute of Justice. DNA Evidence Backlogs – Convicted Offender and Arrestee Samples
4
FBI. CODIS-NDIS Statistics
5
FBI. Quality Assurance Standards for DNA Databasing Laboratories
6
U.S. Bureau of Labor Statistics. Forensic Science Technicians
7
Congress.gov. Sexual Assault Kits and the Backlog of Untested Sexual Assault Evidence
8
Office of the Law Revision Counsel. 18 USC 3297 – Cases Involving DNA Evidence
9
Office of the Law Revision Counsel. 18 USC 3161 – Time Limits and Exclusions
10
National Institute of Justice. Evidence Storage Conditions
11
Office of the Law Revision Counsel. 18 USC 3600 – DNA Testing
12
Office of the Law Revision Counsel. 34 USC 40727 – Kirk Bloodsworth Post-Conviction DNA Testing Grant Program
13
SAM.gov. DNA Backlog Reduction Program
14
Office of the Law Revision Counsel. 34 USC 12591 – Quality Assurance and Proficiency Testing Standards
15
FBI. Guide to All Things Rapid DNA
16
Congress.gov. H Rept 115-117 – Rapid DNA Act of 2017