The key question when recovering a body from a fire is: Did this person die before or as a result of the fire? The corollary question is: If the person was dead before the fire, could the fire be a cover-up for murder? In the reported case, the answer to the main question was revealed during the autopsy. The fact that soot was found in the nose, mouth, trachea, and bronchi is incontrovertible evidence that the victim was ventilating (i.e., breathing) when the fire was started. That the defense would question the validity of the carboxyhemoglobin measurement is simply a way to obscure the facts and divert attention away from the true findings. That said, a carboxyhemoglobin concentration of 61% is consistent with the victim being alive before the fire was set. The laboratory results obtained must be interpreted in the context of the entire case, including the circumstances of death, the autopsy findings, and any relevant medical history.
A carboxyhemoglobin concentration >50% is generally accepted as evidence in itself to account for death; however, patients with medical conditions that compromise cardiac and/or respiratory function may succumb at much lower carboxyhemoglobin concentrations. With the advances in the technology, CO-oximetry is a reliable method for measuring carboxyhemoglobin and can provide accurate results with postmortem samples. The case described by Olson and colleagues provides corroborating evidence that newer instruments with multiple wavelength detectors are appropriate for measuring carboxyhemoglobin in postmortem samples, and results correlate well with those obtained with gas chromatography and ultraviolet spectrophotometry methodologies. In addition, forensic chemists should be aware of confounding factors (e.g., methemoglobin, sulfhemoglobin, low hemoglobin, or turbidity) when measuring carboxyhemoglobin in postmortem blood.
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Authors’ Disclosures of Potential Conflicts of Interest: No authors declared any potential conflicts of interest.
Role of Sponsor: The funding organizations played no role in the design of study, choice of enrolled patients, review and interpretation of data, or preparation or approval of manuscript.
- © 2010 The American Association for Clinical Chemistry