How Long Does DNA Testing Take in Criminal Cases?

DNA testing in a criminal case usually takes anywhere from a few weeks to several months, and in backlogged jurisdictions it can stretch past a year. The federal benchmark treats any forensic DNA case still open after 30 days as backlogged, and many public labs routinely exceed that mark.¹ How long your case takes depends on the condition of the sample, the lab’s workload, the kind of analysis needed, and whether anyone is pushing to move it up the queue.

Typical Timeframes by Case Type

The television version, where results come back before the next commercial, is not the real one. Actual timelines in most public crime labs look like this:

Rush cases in violent crimes with a known suspect: as fast as two days at the best-resourced labs, though two to eight weeks is more common.
Standard cases with a suspect: roughly 20 days to several months, depending on backlog.
Cases without a suspect that require a CODIS search: three weeks to nine months or longer, because a profile has to be generated and then run against the database.
Property crimes: often the lowest priority, with times ranging from 20 days to two years at the extremes.

Some labs move single-source samples through in under 30 days and mixtures in under 60, but that is the exception rather than the norm. The 30-day federal benchmark reflects what the government considers acceptable, and many jurisdictions fall well short of it.¹

What Controls the Timeline

The bench work itself can be done in days under ideal conditions. What stretches a case into months is almost always something outside the lab bench.

Sample Quality

A clean blood sample from a sealed indoor scene is straightforward. A trace of skin cells on a doorknob left in the sun for a week is not. UV light is the single biggest destroyer of DNA on surfaces, and hot, humid outdoor conditions degrade samples far faster than cool, dry indoor ones.² Degraded or contaminated samples force analysts to run additional rounds of amplification, try specialized extraction methods, or start over. Mixed samples containing DNA from more than one person add more time still, because analysts have to separate and interpret overlapping profiles.

Laboratory Backlog

This is where most of the waiting happens. Public forensic labs are chronically underfunded relative to the volume of cases they take in. The federal DNA Capacity Enhancement for Backlog Reduction program calls any case not completed within 30 days of receipt backlogged, and applies the same threshold to database samples that have not been uploaded to CODIS.¹ Turnaround times at state crime labs have been documented from under 15 days for rush cases with a known suspect to two years for some property cases.

Type of Analysis

Standard short tandem repeat analysis, which produces the profiles used in CODIS, is the workhorse. It is well established and comparatively fast. Whole genome sequencing, Y-chromosome analysis for male contributors in sexual assault cases, and mitochondrial DNA testing for highly degraded remains all take longer and require specialized equipment and expertise.

Chain of Custody

Every person who handles a piece of evidence must be identified, and every period of custody must be recorded. If a gap turns up, the evidence may need to be retested or challenged, adding weeks or months. Without a complete chain of custody, results may be excluded from trial or given less weight by a jury.³

When Rapid DNA Applies

Rapid DNA is the closest thing to the TV version. Fully automated machines can generate a profile from a cheek swab in about 90 minutes, at a police booking station, without sending anything to an outside lab.⁴ The Rapid DNA Act of 2017 authorized the FBI to set standards for these instruments and allowed profiles from approved machines to be uploaded directly into CODIS.⁵

The catch: Rapid DNA works only on clean, single-source samples like cheek swabs. It is not designed for the messy, degraded, or mixed samples that come off a weapon or a crime scene. It can quickly tell investigators whether a newly booked person’s DNA matches an unsolved case in CODIS, but it will not resolve a complicated mixture. For most evidence, the standard lab pipeline still applies.

How to Move a Case Up the Queue

Prioritization

Forensic labs prioritize by severity. Homicides and sexual assaults almost always jump ahead of burglaries and car thefts. If you are a defendant or a victim in a serious case, the lab may already be treating your case as urgent. Defense attorneys and prosecutors who communicate directly with lab leadership about trial dates and the stakes involved can sometimes push a case forward. Squeaky wheels matter here.

Private Laboratories

When the public-lab backlog is unacceptable, either side can hire a private forensic lab. Private labs advertise faster turnaround because they are not carrying the same caseload. Costs vary widely: general forensic testing often runs a few hundred dollars, and court-admissible analysis can reach $1,500 or more. Defendants who cannot pay may still have a route through the right to expert assistance discussed below.

Federal Grant Funding

Two federal programs fund lab improvements aimed at cutting backlogs. The Paul Coverdell Forensic Science Improvement Grants Program gives money to state and local labs to improve the quality and speed of forensic services.⁶ The DNA Capacity Enhancement for Backlog Reduction program specifically targets DNA backlogs, funding equipment, analysts, and technology upgrades.¹ These grants have helped, but demand keeps rising as the technology becomes more sensitive and applicable to more types of cases.

Your Rights When Testing Drags On

If you are sitting in jail waiting for DNA results, a delay is not just an inconvenience. It can implicate constitutional protections your attorney should be raising.

Speedy Trial

The Sixth Amendment guarantees the right to a speedy trial. Courts weigh delays using the four-factor balancing test from Barker v. Wingo: the length of the delay, the reason for it, whether the defendant asserted the right, and whether the delay caused prejudice.⁷ A DNA backlog is treated as a “neutral” reason: it is not deliberate stalling, but it is not a valid justification either, because the government bears responsibility for the capacity of its own laboratories.⁸ A backlog weighs against the prosecution, just less heavily than intentional delay.

Independent Testing

Most jurisdictions let the defense inspect physical evidence held by the prosecution, and several states explicitly allow defendants to retest DNA evidence. Even where no specific statute exists, courts have held that the right to retest is implicit in the broader right to inspect evidence.⁹ If the prosecution is using DNA against you, your attorney can request a portion of the sample for analysis by a private lab. This adds time and cost, but it is one of the most effective ways to challenge DNA evidence.

For defendants who cannot afford an expert, the Supreme Court’s decision in Ake v. Oklahoma established that indigent defendants have a constitutional right to expert assistance at government expense when a particular issue is likely to be significant at trial. That case involved a psychiatric expert, but the principle has been extended to other forensic experts, including DNA analysts, in many courts. A public defender should raise this if independent testing is needed and you cannot pay for it.

Post-Conviction DNA Testing

For people already convicted, the timing question changes shape. More than 200 people in the United States have been exonerated through post-conviction DNA testing after serving an average of 16 years for crimes they did not commit.

Federal law provides a mechanism for federal prisoners to request testing. Under 18 U.S.C. § 3600, a person sentenced for a federal offense can file a written motion for DNA testing if they assert actual innocence, the evidence was not previously tested (or a substantially better method now exists), and the results could raise a reasonable probability that they did not commit the crime.¹⁰ The statute sets hard deadlines in capital cases: testing must be completed within 60 days after the government responds, and the court must order any post-testing procedures within 120 days after that.¹¹

Non-capital federal cases and state cases do not have an equivalent federal hard deadline. The Supreme Court in District Attorney’s Office v. Osborne declined to recognize a freestanding constitutional right to post-conviction DNA testing, though it held that states with existing post-conviction discovery rules may not arbitrarily deny access. Most states have their own post-conviction DNA testing statutes, but timelines and requirements vary widely. Some move quickly once a motion is granted. Others add months or years of procedural wrangling before a sample ever reaches a lab.

Sexual Assault Kits Have Their Own Deadlines

The backlog of untested sexual assault evidence kits became a national scandal over the past two decades, with hundreds of thousands of kits sitting untested in police storage. A growing number of states have responded with laws imposing mandatory deadlines for submitting and processing these kits. Typical requirements include submission to a crime lab within 20 to 30 days of collection and completion of analysis within 90 to 120 days after the lab receives the evidence. These state-mandated timelines are the most aggressive legislative effort to force faster DNA testing in a specific category of case, and they explain why sexual assault results often move faster than other evidence sitting in the same lab.

1
Bureau of Justice Assistance. DNA Capacity Enhancement for Backlog Reduction (CEBR) Program Performance Measures
2
National Institute of Justice. Persistence of Touch DNA for Analysis
3
National Institute of Justice. Law 101 Legal Guide for the Forensic Expert – Chain of Custody
4
FBI. Combined DNA Index System (CODIS)
5
Congress.gov. HR 510 – Rapid DNA Act of 2017
6
Bureau of Justice Assistance. Paul Coverdell Forensic Science Improvement Grants Program – About the Program
7
Justia U.S. Supreme Court. Barker v Wingo, 407 US 514 (1972)
8
Constitution Annotated. Reason for Delay and Right to a Speedy Trial
9
National Institute of Justice. Defendants Right to Retest DNA Evidence
10
Office of the Law Revision Counsel. 18 US Code 3600 – DNA Testing
11
GovInfo. Justice for All Act of 2004