What is a significant downside of using Hematrace as a blood test?

The significant downside of using Hematrace as a blood test lies in its tendency to produce false positives when testing for human blood in samples derived from primate sources. This issue arises because Hematrace employs an antibody-based detection method aimed at identifying human hemoglobin. However, the structural similarities between human and primate hemoglobins can lead to the misidentification of primate blood as human blood, complicating forensic investigations.

Accurate blood identification is crucial in crime scene investigations, as confirming whether blood belongs to a human or another species can greatly influence the direction of the case. A false positive could mislead investigators, potentially leading to wrongful assumptions about the nature of the crime or the individuals involved.

In contrast, the other choices do not accurately reflect the limitations of Hematrace. It is designed specifically for human blood detection, hence indicating it can only detect human blood accurately is more of a characteristic than a downside. Moreover, the device is effective in varied lighting conditions and does not specifically require a large blood sample, making those options less relevant in assessing the limitations of Hematrace in forensic contexts.