DNA Databases, CODIS & Forensic Science Programs

The federal DNA database system — the Combined DNA Index System (CODIS) — is the world's largest forensic DNA database, containing over 22 million offender profiles, 5 million arrestee profiles, and 1.3 million forensic (crime scene) profiles as of 2026. Authorized by the DNA Identification Act of 1994 (34 U.S.C. § 12592) and expanded by subsequent legislation, CODIS is maintained by the FBI and links DNA databases at the local, state, and national levels — enabling law enforcement to compare crime scene DNA evidence against known offender and arrestee profiles to identify perpetrators and exonerate the innocent. The system has produced over 750,000 "hits" (matches between forensic evidence and known profiles) since its inception. Congress has supported CODIS through major grant programs: the Debbie Smith DNA Backlog Grant Program (34 U.S.C. § 40701) provides approximately $151 million per year to reduce the backlog of untested DNA evidence (estimated at hundreds of thousands of rape kits and crime scene samples), while the Kirk Bloodsworth Post-Conviction DNA Testing Grant Program (34 U.S.C. § 40727) funds DNA testing for inmates who may be innocent — named for the first death-row inmate exonerated by DNA evidence. These programs have fundamentally transformed criminal justice — solving cold cases decades old and freeing approximately 370+ wrongfully convicted people through post-conviction DNA testing (the National Registry of Exonerations counts 367 DNA exonerations as of 2025; the Innocence Project marked the 375 milestone in 2020). See Habeas Corpus & Post-Conviction for how inmates seek relief, and Federal Sentencing Guidelines for the sentencing framework these cases operate within.

Current Law (2026)

Legal Authority

• 34 U.S.C. § 12592 — Index to facilitate law enforcement exchange of DNA identification information (authorizes the FBI Director to establish a national DNA index system — CODIS — for exchange of DNA identification records; sets quality assurance standards and privacy protections)
• 34 U.S.C. § 40701 — Debbie Smith DNA Backlog Grant Program (provides grants to states and localities for analyzing DNA evidence from crime scenes and offenders; named for a rape survivor whose assailant was identified through DNA evidence years after the crime)
• 34 U.S.C. § 40702 — Collection from federal offenders (requires DNA collection from all individuals convicted of qualifying federal offenses and from all federal arrestees; DNA profiles are entered into CODIS)
• 34 U.S.C. § 40706 — Privacy protection standards (restricts use of DNA samples and records to law enforcement identification purposes; prohibits disclosure for non-identification purposes; requires expungement procedures for profiles of individuals who are not convicted)
• 34 U.S.C. § 40722 — DNA training and education (grants for training law enforcement, correctional personnel, and court officers on DNA evidence collection, preservation, and use)
• 34 U.S.C. § 40726 — DNA identification of missing persons (authorizes use of DNA technology to identify missing persons and unidentified human remains)
• 34 U.S.C. § 40727 — Kirk Bloodsworth Post-Conviction DNA Testing Grant Program (grants to states for post-conviction DNA testing in cases where DNA evidence may demonstrate actual innocence)

How It Works

CODIS operates at three hierarchical levels: local DNA index systems (LDIS) at crime laboratories, state DNA index systems (SDIS) maintained by each state, and the national DNA index system (NDIS) at the FBI. DNA profiles entered at the local level flow up to the state and national databases, and when a new profile is entered — from a crime scene, a convicted offender, or an arrestee — CODIS automatically searches for matches across all levels. A "hit" links a forensic profile from an unsolved crime to an offender or arrestee, potentially identifying the perpetrator. CODIS uses a standardized set of 20 genetic markers (loci) — sufficient for individual identification but designed not to reveal medical conditions, physical traits, or family relationships. One of the most persistent problems the program addresses is the DNA testing backlog: hundreds of thousands of rape kits, crime scene samples, and offender samples have sat untested in labs and evidence rooms, each representing a potential solved case or a serial offender still committing crimes. The Debbie Smith DNA Backlog Grant Program (34 U.S.C. § 40701) funds state and local labs to process these backlogs; since enactment, grants have funded the analysis of hundreds of thousands of previously untested samples.

Post-conviction DNA testing has been transformative for wrongful conviction cases. The Kirk Bloodsworth Post-Conviction DNA Testing Grant Program (34 U.S.C. § 40727) funds testing for convicted inmates who maintain their innocence where biological evidence was never tested or where newer methods could reveal exculpatory results. Since forensic DNA testing began in the late 1980s, over 365 people have been exonerated through DNA (367 per the National Registry of Exonerations as of 2025) — including 21 who were on death row — exposing the fragility of eyewitness identification, false confessions, and pre-DNA forensic methods like bite mark analysis and hair microscopy. Federal law prohibits using CODIS profiles for any purpose other than law enforcement identification, and individuals arrested but not convicted are entitled to expungement of their profiles — though enforcement of expungement requirements varies significantly by state.

How It Affects You

If you're a crime victim with an unsolved case: If DNA evidence was collected from your assault or other crime but no suspect was ever identified, ask the detective assigned to your case — or your prosecutor's office — whether that evidence has been submitted to the state crime lab for CODIS analysis. DNA evidence in evidence rooms doesn't automatically get uploaded to CODIS; it must be tested first, and testing backlogs have historically meant evidence sits for years. The Debbie Smith DNA Backlog Grant Program (34 U.S.C. § 40701) has funded the analysis of hundreds of thousands of previously untested samples — your case may have benefited, or may benefit if you push for testing.

You have a right to ask for updates on your case under the Crime Victims' Rights Act (18 U.S.C. § 3771) — including the right to be informed if a CODIS hit occurs. Request to be notified immediately if a DNA match is identified. If your case is a cold case (no active investigation), contact your state crime lab and the detective division of the law enforcement agency that investigated your case to ask specifically about the status of DNA testing. For sexual assault cases, many states now have a "Survivor's Bill of Rights" that gives victims the right to ask about the status of their rape kit specifically.

If you or someone you know may have been wrongfully convicted: Post-conviction DNA testing has exonerated over 365 people nationwide, including 21 who were on death row. If DNA evidence exists from the crime (biological samples, touch DNA from surfaces, hair) that was never tested or was tested with older methods, a DNA test today could produce a different result — either because the technology is more sensitive or because CODIS now contains profiles that weren't in the database at the time of trial.

The pathway: (1) Contact the Innocence Project (innocenceproject.org) — they provide free representation for wrongful conviction cases with DNA evidence, and can evaluate whether a case qualifies for post-conviction testing. (2) The Kirk Bloodsworth Post-Conviction DNA Testing Grant Program (34 U.S.C. § 40727) funds state programs that provide testing in qualifying cases — your state may have an office or program to apply to directly. (3) Some states have enacted statutes creating a right to post-conviction DNA testing — check your state's statute (all 50 states have some form of post-conviction DNA testing access, though the procedural requirements vary significantly). Federal inmates have access under the Innocence Protection Act (18 U.S.C. § 3600), which requires the government to preserve DNA evidence and grants federal convicts the right to apply for testing.

If you were arrested by federal authorities but not convicted: Federal law (34 U.S.C. § 40706) entitles you to expungement of your CODIS profile if: charges were dismissed, you were acquitted, or the conviction was overturned. The expungement isn't automatic — you must request it. Contact the U.S. Marshals Service or the arresting federal agency to initiate the expungement request. State laws on expungement of CODIS profiles for state arrests vary considerably — some states require court orders, others have administrative procedures, and some have significant procedural barriers for expungement even after acquittal. If you were arrested in a state that collects DNA upon arrest (about 30 states authorized this after Maryland v. King, 2013), verify that your state has actually expunged your profile after a non-conviction outcome — the burden typically falls on you to follow up.

If you're a law enforcement official, prosecutor, or crime lab professional: CODIS is most effective when forensic evidence is collected, preserved, and submitted promptly. Every day a rape kit sits untested is a day a serial offender may be committing additional crimes — serial offenders are responsible for a disproportionate share of violent crimes, and CODIS cold hits often connect cases across jurisdictions. Best practices: (1) Establish a protocol for automatic submission of all sexual assault kit evidence to the crime lab within a specified timeline (30–60 days is a common standard); (2) Ensure investigators request CODIS searches specifically — not just the issuance of a report, but a search against NDIS; (3) Use investigative genetic genealogy (IGG) for cold cases where the CODIS search hasn't produced a hit — IGG searches consumer genetic databases for familial DNA matches, which can identify perpetrators through relatives. DOJ's interim policy on IGG (issued 2019) requires supervisory approval for IGG use and prohibits its use in non-violent cases without special authorization. Submit DNA evidence from cold cases to labs with IGG capability when standard CODIS hits have been exhausted.

State Variations

CODIS is a national system, but state laws govern DNA collection:

• All 50 states require DNA collection from convicted felons; the qualifying offenses vary
• About 30 states authorize DNA collection upon felony arrest (upheld by the Supreme Court in Maryland v. King, 2013)
• State laws vary on which offenses trigger DNA collection, when samples are collected, and expungement procedures
• State crime labs receive Debbie Smith grants but face varying backlog challenges
• Post-conviction DNA testing access varies by state — some states have robust testing statutes; others create significant procedural barriers

Implementing Regulations

• 28 CFR Part 28 — DNA Identification System: the DOJ regulations implementing the DNA Analysis Backlog Elimination Act and the Justice for All Act's mandatory DNA collection and biological evidence preservation requirements. Part 28 covers two distinct frameworks:

  Subpart B — Federal offender DNA collection (§§ 28.11–28.13):

  • § 28.12 — Collection obligation: the Bureau of Prisons must collect a DNA sample from every individual in BOP custody who has been convicted of any federal felony; the U.S. Probation Office and Parole Commission must collect samples from qualifying individuals under their supervision; collection is by buccal swab (cheek swab) and is mandatory — refusal is a Class A misdemeanor; the scope of qualifying offenses has expanded from serious violent crimes (original law) to all federal felonies, reflecting Congress's view that expanding the database serves law enforcement interests in solving crimes committed after incarceration or probation
  • § 28.13 — FBI analysis and NDIS indexing: the FBI carries out DNA analysis on samples furnished by BOP and probation; analyzed profiles are indexed in the NDIS (National DNA Index System) — the national CODIS tier; NDIS profiles are available to all law enforcement agencies participating in CODIS for forensic comparison; the indexing creates the population of known offender profiles against which crime scene evidence is compared in the identification workflow

  Subpart C — Biological evidence preservation (§§ 28.21–28.28) (implementing 18 U.S.C. § 3600A):

  • § 28.22 — Preservation requirement: the federal government must preserve all biological evidence secured in connection with the investigation or prosecution of a federal crime as long as any person remains incarcerated in connection with that crime; "biological evidence" includes sexual assault kits, blood and tissue samples, hair samples, touch DNA samples, and other biological materials containing genetic material that may be subject to DNA testing
  • § 28.23 — What evidence is covered: the preservation obligation attaches to biological evidence that was tested OR that was secured in connection with the investigation or prosecution regardless of whether it was tested at the time of trial; untested biological evidence from a federal conviction must be preserved — this is the most important provision for post-conviction DNA testing, because it requires the government to retain evidence that might exonerate a defendant even decades after conviction
  • §§ 28.24–28.26 — Exceptions: the preservation obligation does not apply if: a court has already determined that no right to testing exists; the defendant has declined testing; the evidence is so small that testing would consume it all; or the evidence was lost before the preservation requirement took effect; the exception for defendant's consent to destruction (§ 28.25) means defendants must be informed before evidence is destroyed and have an opportunity to object — providing a procedural protection for future post-conviction testing rights
  • § 28.28 — Sanctions: violations of the biological evidence preservation requirement by government employees are subject to disciplinary sanctions under civil service law; knowing destruction of biological evidence to prevent DNA testing can also constitute obstruction of justice under 18 U.S.C. § 1512; the combination of disciplinary and criminal sanctions is designed to deter evidence destruction that would foreclose post-conviction testing

  The biological evidence preservation subpart was enacted after multiple high-profile cases in which potentially exonerating DNA evidence had been destroyed after conviction — preventing prisoners from obtaining testing that might have established innocence. States have varying biological evidence preservation laws; the federal preservation requirement applies only to federal prosecutions. The DNA collection subpart creates the supply of reference profiles that makes CODIS forensic matching work — without a comprehensive database of offender profiles, crime scene DNA evidence cannot be matched to known individuals.

• FBI Quality Assurance Standards for Forensic DNA Testing Laboratories — technical standards for all laboratories participating in CODIS, covering proficiency testing, validation requirements, analyst qualifications, and chain-of-custody protocols

• 42 USC 14135a implementing guidance — DOJ procedures governing DNA collection from federal offenders and arrestees, including collection methods, sample handling, and submission to CODIS

Pending Legislation

DNA database and forensic science provisions appear in broader criminal justice legislation — see Criminal Justice Reform and Forensic Science.

Recent Developments

The use of genetic genealogy (comparing crime scene DNA to consumer genetic databases like GEDmatch and FamilyTreeDNA) has revolutionized cold case investigations — most famously leading to the arrest of the Golden State Killer in 2018. This technique raises new data privacy questions not addressed by existing DNA database laws, as it uses familial DNA from voluntary consumer databases rather than CODIS. DOJ issued interim guidance on investigative genetic genealogy in 2019, establishing procedural requirements. The Debbie Smith Act was most recently reauthorized in 2019. FBI has continued to expand CODIS capacity and update the core genetic markers used for profiling. Rapid DNA technology — which can generate DNA profiles in under 2 hours at booking stations rather than sending samples to a lab — is being deployed in an increasing number of jurisdictions.