What can a DNA expert actually do?

A DNA expert reviews, explains, and evaluates DNA evidence to determine what the findings genuinely show - and what they do not.

This can involve examining how samples were collected, what areas were tested, and whether the sampling strategy was appropriate in light of the allegation. It may include reviewing DNA profiles, mixed results, low-level findings, and the analytical methods used to generate them.

Experts also assess statistical interpretation, including likelihood ratios, modelling assumptions, and how strongly results are presented. In some cases, the way statistics are applied can materially affect how the evidence should be understood.

Handling and contamination are further areas of review. This may include evaluating collection methods, packaging, storage, and laboratory processes to identify opportunities for transfer or the introduction of DNA.

Importantly, a DNA expert considers the evidence at the level of activity — not just source. This means evaluating whether the scientific findings fit with the alleged events, whether alternative explanations exist, and whether conclusions drawn from the results are proportionate to the science.

A DNA expert may also:

• identify issues requiring further testing or clarification
• review report wording and evidential strength
• assist legal teams in understanding the significance of findings
• provide expert opinion for court where required

The role is to ensure the evidence is accurately interpreted, properly contextualised, and relied upon appropriately within the case.