DNA evidence is used in less than 1% of all criminal cases. Despite that small fraction, it has an outsized impact on the justice system, helping solve violent crimes, identify repeat offenders, and free people who were wrongly convicted. The gap between how often DNA appears on crime dramas and how often it’s actually used in real investigations is enormous.
Why Less Than 1% of Cases
Most criminal cases simply don’t involve the kind of biological evidence that DNA testing requires. A shoplifting charge, a DUI, a drug possession case, a fraud prosecution: none of these typically produce blood, saliva, skin cells, or other material worth sending to a lab. DNA analysis is expensive, time-consuming, and only useful when biological material is recovered from a crime scene, a victim, or an object connected to the crime.
One project that generated 285 DNA profiles for the national database cost roughly $286,000 in total, factoring in both lab processing and the scientist time needed to prepare cases and upload results. That works out to about $1,000 per usable profile. With millions of criminal cases moving through U.S. courts each year, testing every one would be neither practical nor necessary. Labs prioritize cases where DNA can actually change the outcome, which usually means serious violent crimes like sexual assaults and homicides.
Where DNA Makes the Biggest Difference
The cases where DNA evidence does appear tend to be the highest-stakes ones. Rape and murder investigations are the most common settings for DNA collection because these crimes frequently leave behind biological material and because the consequences of a wrong verdict are severe. In these cases, a DNA match can be the single most persuasive piece of evidence presented at trial.
Property crimes are a different story, but a revealing one. A National Institute of Justice study compared burglary investigations that used DNA evidence against those relying on traditional police work alone. When DNA was collected and analyzed, a suspect was identified in 31% of cases. When DNA was collected but left untested for at least two months, that figure dropped to just 12%. DNA more than doubled the identification rate for burglaries, yet most police departments still don’t routinely collect biological evidence at break-in scenes because of cost and lab capacity.
The FBI’s National DNA Database
The backbone of forensic DNA work in the United States is CODIS, the FBI’s Combined DNA Index System. As of November 2025, the national database holds over 19.2 million offender profiles, 6.1 million arrestee profiles, and nearly 1.5 million forensic profiles collected from crime scenes. When investigators submit a DNA sample, it’s run against this database looking for a match.
CODIS has produced over 781,000 hits and assisted in more than 758,000 investigations since its creation. A “hit” means a crime scene sample matched either a known offender’s profile or another crime scene sample, giving investigators a lead they wouldn’t have had otherwise. Those numbers represent cases where DNA moved an investigation forward, connecting crimes to suspects or linking separate cases together.
Genetic Genealogy: When CODIS Fails
When a DNA profile doesn’t match anyone in CODIS, investigators increasingly turn to forensic genetic genealogy. This technique, which gained public attention after the 2018 arrest of the Golden State Killer, involves uploading crime scene DNA to public genealogy databases and tracing family trees to identify potential suspects.
An estimated 500 or more cases have benefited from forensic genetic genealogy, with roughly 439 resolved through investigative leads generated by this method before the end of 2020. Under U.S. Department of Justice policy, a case must first fail to produce a CODIS match before investigators can pursue genetic genealogy. It remains a tool of last resort, used in cold cases and serious unsolved crimes rather than routine investigations.
Freeing the Wrongly Convicted
DNA’s role isn’t limited to putting people behind bars. It has also freed them. The Innocence Project has documented 353 post-conviction DNA exonerations in the United States. These are people who were convicted of crimes they did not commit, sometimes spending years or decades in prison before DNA testing proved their innocence.
The average exoneree served 14 years before being cleared. Twenty of the 353 had been sentenced to death. Perhaps most striking, 38 of them had pleaded guilty to crimes they never committed, illustrating how flawed the system can be even when a defendant appears to accept responsibility. DNA exonerations have reshaped how courts, police departments, and prosecutors think about the reliability of eyewitness testimony, confessions, and other traditional forms of evidence.
The First Case That Started It All
DNA profiling entered criminal investigations in 1986, when British police asked geneticist Alec Jeffreys to help solve the rapes and murders of two girls. His DNA tests first exonerated the primary suspect, a man who had confessed under pressure. Police then conducted a mass DNA screening of local men, and the actual perpetrator, Colin Pitchfork, was caught after he tried to have a friend submit a blood sample in his place. That single case demonstrated both of DNA’s most powerful functions: clearing the innocent and identifying the guilty.
In the nearly four decades since, forensic DNA has evolved from an experimental technique into one of the most trusted tools in criminal justice. But its reach remains narrow. For the vast majority of cases moving through the courts on any given day, DNA plays no role at all. Its power is concentrated in the small percentage of investigations where biological evidence exists, where labs have the capacity to test it, and where the stakes justify the cost.