The DNA Beneath the Fingernails: What the Murdaugh Retrial Can—and Cannot—Prove

On 16 October 2026, a South Carolina judge allowed Alex Murdaugh’s defence team to independently test unidentified male DNADNA, or Deoxyribonucleic Acid, is the genetic material found in cells, composed of a double helix structure. It serves as the genetic blueprint for all living organisms. Read Full Definition recovered beneath Maggie Murdaugh’s fingernails. It is the kind of development that immediately generates a dramatic headline: unknown DNA, a contested murder conviction, and a second trial approaching. Scientifically, however, the central question is not simply whether another man’s DNA was present. It is what that presence can reliably tell us about the killings.

From my perspective as a forensic DNA analystA designated person who examines and analyzes seized drugs or related materials, or directs such examinations to be done; independently has access to unsealed evidence in order to remove samples from the evidentiary material for Read Full Definition, this is where the case becomes especially instructive. A DNA profile can address the possible biological source of a trace. It does not, by itself, reveal when the material was deposited, how it arrived, whether it was connected with violence, or whether its contributor was present when the crime occurred. Those are different propositions requiring different evidenceEvidence is any form of proof, such as objects, materials, or scientific findings, presented to establish or disprove a fact in a legal proceeding. It is used to reconstruct events and link or exclude individuals Read Full Definition.

The essential forensic distinction: identifying a possible DNA contributor is a source-level question. Deciding whether the DNA resulted from an assault, routine contact, indirect transfer, or contaminationContamination - The unwanted transfer of material from another source to a piece of physical evidence. The inadvertent touching of a weapon, thereby adding fingerprints to it is an example of evidence contamination. Read Full Definition is an activity-level question.

This article examines the publicly reported evidence, the scientific difficulties of fingernail DNA, the safeguards required when only a small quantity of material remains, and the conclusions that neither side should draw prematurely. Because the retrial is pending, allegations and defence claims discussed here remain unproven unless established in court.

A murder case returning to court

Margaret “Maggie” Murdaugh and her son Paul were shot and killed on 7 June 2021 near the dog kennels at the family’s Moselle property in South Carolina. Alex Murdaugh, Maggie’s husband and Paul’s father, called emergency services after reporting that he had found their bodies.

State prosecutors later allegedAlleged is a term used in legal contexts to describe an accusation or claim that has been made against an individual but has not yet been proven or confirmed. Read Full Definition that Murdaugh killed them as mounting scrutiny threatened to expose years of financial theft. The defence maintained that he did not commit the murders. In March 2023, a jury convicted him of two murders and two weapons offences, and he received consecutive life sentences.

Those convictions are no longer legally operative. On 13 May 2026, the South Carolina Supreme Court reversed the denial of a new trial. The court held that Colleton County Clerk of Court Rebecca Hill improperly influenced the jury and that the State had not rebutted the resulting presumption of prejudice. The ruling ordered a new trial; it did not declare Murdaugh innocent or decide that the prosecution’s evidence was insufficient.

The retrial is scheduled to begin on 5 April 2027 in Sumter County. Murdaugh remains imprisoned under separate state and federal sentences for financial crimes.

Timeline: from the killings to independent DNA testing

• 7 June 2021: Maggie and Paul Murdaugh are killed at the Moselle property.
• 14 July 2022: A South Carolina grand jury indicts Alex Murdaugh on murder and weapons charges.
• 25 January 2023: Opening statements begin in the first murder trial.
• 2 March 2023: The jury finds Murdaugh guilty on all four counts.
• 3 March 2023: He receives two consecutive life sentences for the murders.
• 27 October 2023: The defence moves for a new trial, alleging improper jury influence by the clerk of court.
• 13 May 2026: The South Carolina Supreme Court reverses the murder convictions and remands the case for a new trial.
• 16 October 2026: Circuit Court Judge Debra McCaslin allows independent testing of remaining DNA evidence, including the unidentified male DNA beneath Maggie’s fingernails and swabs associated with her phone.
• 13 November 2026: The next pretrial hearing is scheduled.
• 5 April 2027: The retrial is scheduled to begin. There is currently no retrial verdict.

What the October 16 ruling actually permits

According to the Associated Press, the fingernail material produced a male DNA profile that did not match a member of the Murdaugh family and had not generated a match to another person. The profile was not a major feature of the 2023 trial. The defence requested an opportunity to have the remaining material examined by a private laboratory.

Local reporting from the October 16 evidentiary hearing indicates that relatively little sample remains. Prosecutors raised the possibility that further processing could consume it. Judge McCaslin nevertheless concluded that the potential importance of the evidence justified independent testing.

The court drew a boundary around the defence request. It allowed focused DNA examination but rejected a much broader effort to compile and compare cartridge cases from years of unrelated shootings involving the same broad firearm type. That distinction matters: a party may be entitled to test particular evidence with a plausible connection to the charged offence without receiving unlimited discovery based on speculation.

The forensic deep dive

Why fingernail samples are potentially important

Material collected from beneath a victim’s fingernails can be highly relevant when the circumstances suggest scratching, gripping, defensive contact, or a physical struggle. A victim may acquire cells from another person’s skin, blood, saliva, or other biological material. If a foreign profile is recovered and can be associated with a plausible assailant, it may support an investigative hypothesis.

That is the attractive version of the evidence. The real biological environment is less tidy.

Fingernails also accumulate DNA during everyday life. Handshakes, shared objects, household contact, caregiving, grooming, clothing, phones, pets, and surfaces can all contribute material. A profile may include self-DNA, DNA from close contacts, low-level background contributors, or mixtures. Research on the prevalence and persistence of foreign DNA beneath fingernails demonstrates why the mere presence of non-self DNA cannot be equated automatically with scratching an offender.

Experimental scratching studies are informative but not deterministic. In one frequently cited study, DNA compatible with the scratched person was detected in some fingernail samples collected after deliberate scratching, and recovery decreased as time passed. More recent research has likewise shown that male DNA may persist temporarily beneath a female participant’s fingernails after simulated scratching. These studies demonstrate possibility and persistence under controlled conditions; they do not recreate the full circumstances of the Moselle killings.

The first unanswered question: what kind of profile was obtained?

“Unknown male DNA” is not a complete scientific description. Before assessing its significance, an expert would need the laboratory report, electropherograms, case notes and validationValidation, often referred to as method validation, is a crucial process in the laboratory when introducing a new machine, technology, or analytical technique. It involves a series of systematic steps and assessments to ensure that Read Full Definition context. Important questions include:

• Was the result a complete autosomal STR profile, a partial profile, a Y-STR profile, or a mixture?
• How much DNA was recovered, and what degradation or inhibition indicators were observed?
• How many lociA locus is the precise position of a gene on a chromosome. Different alleles of the same gene occupy the same locus. Read Full Definition produced reportable results?
• Was the male component clearly distinguished from Maggie’s DNA?
• Were allelesAlleles are different forms of a gene resulting from mutations or variations in the DNA sequence or gene expression. They can be dominant (expressed with one copy) or recessive (expressed only with two copies). Read Full Definition close to the analytical or stochastic thresholds?
• Were replicate amplifications performed, and were the findings reproduced?
• What comparison statistic, if any, was calculated?
• Which known individuals and quality-assurance elimination profiles were compared?
• Were all controls acceptable?

A partial low-template profile may exclude members of the Murdaugh family yet still be insufficient to identify anyone else. “No database match” can also be misunderstood. It may mean the contributor is absent from the searched database, that the profile is ineligible or insufficient for searching, or simply that no current database profile meets the applicable matching criteria.

Readers who want a closer examination of why technically similar samples can generate different outcomes should see Why Identical Touch-DNA Samples Produce Different Results Across Laboratories.

Source-level evidence is not activity-level evidence

Suppose independent testing confirms the same unknown male profile. That would strengthen confidence that the original finding was reproducible. It would not establish the activity that produced it.

At source level, the relevant questions might be:

• Could a named person be the contributor?
• How much more probable are the DNA findings if that person contributed rather than an unknown unrelated person?

At activity level, the competing questions could look very different:

• Are the findings more probable if Maggie scratched an attacker during the killings?
• Or are they more probable if the DNA arose through earlier routine contact, handling of a shared object, secondary transfer, or contamination?

The second comparison requires information extending far beyond the genotype. Analysts need the amount and distribution of DNA, the sampling location, relevant contact history, transfer and persistence dataInformation in analog or digital form that can be transmitted or processed. Read Full Definition, timing, opportunities for innocent contact, and the circumstances of recovery. Simply Forensic’s guides to the hierarchy of forensic propositions and the likelihood-ratio framework explain why these questions must not be collapsed into one.

Direct transfer is only one pathway

A contributor does not have to scratch, fight with, or even directly touch a victim for their DNA to reach a fingernail sample. Plausible pathways include:

1. Direct transfer: Maggie directly contacts the person, perhaps through routine social contact or a struggle.
2. Secondary transfer: She contacts an object or person carrying someone else’s biological material.
3. Successive transfer: Material passes through more than one intermediary before recovery.
4. Pre-existing background DNA: The material was already present before the relevant events.
5. Collection or laboratory contamination: DNA is introduced during recovery, packaging, transport or analysis.

Secondary transfer is not merely theoretical. The well-known Lukis Anderson case demonstrated how an innocent person’s DNA could be transported to a homicide victim through shared emergency responders. That does not mean secondary transfer explains the Murdaugh profile. It means the pathway must be evaluated rather than assumed.

For additional examples of persistence and alternative transfer explanations, see Can a Kiss Explain Away DNA on a Cigarette Butt? and Making Sense of DNA Transfer and Activity-Level Modelling.

Contamination must be investigated, not casually alleged

Contamination is sometimes invoked as a universal explanation for an inconvenient result. Scientifically, it should be examined through records and comparisons.

The independent reviewers should examine the scene logs, collection personnel, fingernail-sampling procedure, packaging, evidence-opening history, laboratory batch records, reagent lots, negative controls, staff elimination database and any other samples processed near the evidence. A contamination inquiry asks whether there is a documented pathway and whether the profile corresponds to someone with legitimate access.

The newly published ANSI/ASB Standard 136-26, listed by NIST’s forensic-science standards programme, addresses the prevention, monitoring and mitigation of human-DNA contamination. Its broader lesson applies directly here: contamination risk is managed through documented controls, environmental monitoring, elimination databases and investigation of unexpected results—not through unsupported reassurance or speculation.

Our detailed forensic DNA contamination-control guide explains the quality-system records that should accompany any conclusion about an unexpected profile.

Why the remaining sample creates a special problem

DNA extraction is often consumptive. Once a swab or cellular deposit has been processed, the original biological material may be depleted or destroyed even if an extract remains. When only a small quantity survives, testing must balance the possibility of obtaining new information against the loss of future analytical options.

A defensible limited-sample plan should document:

• the exact item and quantity available before testing;
• the proposed sampling and extraction method;
• whether the item can be divided or an extract aliquotIn the forensic context, the concept of "aliquot" remains applicable but with specific relevance to handling and analyzing forensic samples and evidence. Here's how aliquots are used in forensic investigations: • Evidence Preservation: In forensic Read Full Definition retained;
• which tests will be performed and in what order;
• the method’s expected sensitivityIn the context of laboratory equipment or analytical techniques, the term "sensitive" describes the capability of a machine or method to detect even very small amounts or concentrations of a substance. Sensitivity is a quantitative Read Full Definition and consumption;
• who may observe or document the opening and processing;
• the positive, negative and reagent controls;
• how raw data, notes, software settings and remaining extracts will be preserved; and
• what will happen if the initial result is inconclusive.

The American Bar Association’s DNA-evidence standards specifically address potentially consumptive testing and procedures that permit independent evaluation. National Institute of Justice training materials likewise recognise that laboratories require prior authorisation when testing may consume limited evidence.

Independent testing does not mean testing without shared safeguards. Both parties benefit when the process can later be reconstructed and reviewed.

What methods might a private laboratory consider?

The appropriate method depends on what remains and what earlier testing showed. Conventional autosomal STR analysis may be suitable if enough nuclear DNA survives. If a minor male component is masked by abundant female DNA, Y-STR analysis may assist in detecting a paternal-line profile, although it cannot individualise men from the same paternal lineage and generally carries less discrimination than a full autosomal profile.

A laboratory might also consider a more sensitive amplification strategy or sequencing-based analysis, but greater sensitivity is not automatically better. It may recover additional low-level contributors whose connection to the offence is even harder to interpret. Every method must be validated for the sample type, quantity and intended conclusion.

SNP analysis or forensic genetic genealogy should not be treated as the automatic next step. Those approaches require sufficient data quality, appropriate legal authority, privacy safeguards, a suitable database pathway and eventual confirmation with conventional evidence. The October 16 ruling authorises testing; public reporting does not establish that genealogy testing has been ordered or is technically feasible.

What different retesting outcomes would mean

Arrest, first trial, overturned verdict and retrial

Murdaugh was indictedAn indictment is an official accusation stating that a person is being charged with a crime and that a criminal trial will be held. Read Full Definition in July 2022 while already facing extensive financial-crime proceedings. At the first murder trial, prosecutors relied on a circumstantial case that included digital evidence placing him near the kennels shortly before the deaths, changes in his account of his movements, firearms and ammunition evidence, and the alleged financial motive. Murdaugh testified and denied killing Maggie and Paul while acknowledging that he had lied to investigators about his presence at the kennels.

The jury convicted him on 2 March 2023. The South Carolina Supreme Court’s 2026 decision did not resolve the factual dispute over the killings. It held that external influence on the jury violated the right to a fair trial. The case therefore returns to a new jury, where the State must again prove the charges beyond a reasonable doubt and the defence may challenge both the original evidence and newly tested material.

There is currently no final murder verdict following the appellate reversal. Describing Murdaugh as presently convicted of these murders would be legally inaccurate, even though he remains incarcerated for separate crimes.

An analyst’s perspective: four lessons from the DNA dispute

1. “Unknown” describes a comparison result, not a criminal role

An unidentified profile may come from an offender, an innocent contact, background material or contamination. Its narrative significance must not be embedded in the label.

2. Reproducibility strengthens the analytical finding—not necessarily the prosecution or defence story

If the private laboratory reproduces the profile, confidence in its existence increases. The activity-level explanation remains a separate evaluation.

3. Limited evidence demands a jointly reviewable plan

When testing could consume the final material, the method, sequence, observation arrangements and data-disclosure rules should be fixed before the package is opened.

4. The most important evidence may be the documentation around the profile

Electropherograms, controls, collection notes, batch records and elimination comparisons can reveal whether the finding is robust and what alternative explanations require serious consideration. A short verbal description cannot substitute for the complete technical record.

This case reinforces a principle that is easy to state and difficult to maintain in a courtroom: DNA is powerful because it answers defined questions. It becomes misleading when it is asked to answer questions that the biology and data cannot resolve.

Frequently asked questions

Does unknown male DNA beneath Maggie Murdaugh’s fingernails prove another man killed her?

No. It establishes, at most, that male DNA not attributed to the compared family members was detected. Its relevance depends on profile quality, transfer pathway, timing, contamination controls and connection to a named person or event.

Why did the DNA not match anyone in a database?

The contributor may not be represented in the searched database, or the profile may not meet the technical or legal requirements for a useful search. “No match” does not mean the contributor is unknowable or necessarily unrelated to the case.

Can fingernail DNA come from innocent contact?

Yes. Foreign DNA may accumulate through ordinary direct contact, shared objects, household activity or secondary transfer. Its quantity and persistence vary, so the complete circumstances must be evaluated.

Why could independent testing consume the evidence?

Extraction removes biological material from the original sample, and amplification uses part of the resulting extract. With a very small deposit, little or nothing may remain for another attempt. That is why a consumption plan and comprehensive documentation are essential.

Would a match to another person exonerate Murdaugh?

Not automatically. Investigators would need to determine whether that person had an innocent reason for contact, when transfer could have occurred, and whether other evidence connects the individual to the killings. The match would have to be evaluated alongside the entire case.

Why was the original conviction overturned?

The South Carolina Supreme Court found that improper comments by the clerk of court created an unrebutted presumption that the jury’s verdict may have been influenced. The decision concerned the fairness of the trial process; it was not a scientific finding about the unknown DNA and did not declare Murdaugh innocent.

Sources and further reading

• Associated Press: evidence dispute and independent DNA testing, 16 October 2026
• Supreme Court of South Carolina: State v. Murdaugh, opinion filed 13 May 2026
• WCSC: rulings from the October 16 pretrial hearing
• Forensic Science International: Genetics: prevalence and persistence of foreign DNA beneath fingernails
• Forensic Science International: Genetics: male DNA transfer and persistence after simulated scratching
• NIST OSAC Registry: ANSI/ASB Standard 136-26 on human-DNA contamination control
• American Bar Association: standards on DNA evidence and consumptive testing

Editorial note: This article analyses publicly available information about a pending criminal case. Alex Murdaugh’s 2023 murder convictions were reversed, and the charges will be determined at a new trial. Scientific possibilities discussed here should not be read as findings about how the unidentified DNA was deposited.