Sara Zapata

Sara Zapata testified for the State as a SLED forensic scientist. She explained touch DNA, mixed profiles, STRmix likelihood ratios, and the limits of drawing conclusions about body-fluid source, timing, or transfer from a DNA result.

On direct examination, Zapata presented DNA comparisons involving ammunition, firearms, vehicle and clothing samples, fingernail clippings, and other collected evidence. Her results supported Margaret Murdaugh or Paul Murdaugh as contributors to several items and supported both Margaret and Richard Alexander Murdaugh in one mixed profile. The raincoat produced no interpretable contributor result.

Testing of the white T-shirt became a central subject of examination. Zapata reported that confirmatory Hematrace testing found no human blood on the tested shirt items despite earlier presumptive positives. She discussed research concerning possible interaction with LCV but declined to interpret alleged blood-spatter patterns because that analysis was outside her expertise. Later testimony linked her confirmatory report to the correction of an earlier grand-jury representation about blood spatter on the shirt.

The defense also questioned Zapata about three low-level foreign alleles beneath one set of Margaret Murdaugh's fingernail clippings. She said one indicated a male contributor and excluded Paul and Alex Murdaugh, but the limited profile was insufficient for CODIS and could not establish when or how the DNA arrived. On redirect and recross, she reiterated that DNA analysis cannot determine the time or manner of deposit and agreed that touch DNA arising from the ordinary-contact scenarios posed by the defense would not be uncommon.