Abstract
Presumptive tests for blood play a critical role in the examination of physical evidence and in the determination of subsequent analysis. The catalytic power of hemoglobin allows colorimetric reactions employing phenolphthalein (Kastle-Meyer test) to indicate "whether" blood is present. Consequently, DNA profiles extracted from phenolphthalein-positive stains are presumed to be from blood on the evidentiary item and can lead to the identification of "whose" blood is present. Crushed nodules from a variety of legumes yielded phenolphthalein false-positive reactions that were indistinguishable from true bloodstains both in color quality and in developmental time frame. Clothing and other materials stained by nodules also yielded phenolphthalein false-positive reactivity for several years after nodule exposure. Nodules from leguminous plants contain a protein (leghemoglobin) which is structurally and functionally similar to hemoglobin. Testing of purified leghemoglobin confirmed this protein as a source of phenolphthalein reactivity. A scenario is presented showing how the presence of leghemoglobin from nodule staining can mislead investigators.
Original language | English (US) |
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Pages (from-to) | 481-484 |
Number of pages | 4 |
Journal | Journal of Forensic Sciences |
Volume | 59 |
Issue number | 2 |
DOIs | |
State | Published - Mar 2014 |
Externally published | Yes |
Keywords
- Blood test
- Bloodstain
- DNA extraction
- DNA typing
- False-positive
- Forensic science
- Hemastix
- Hemoglobin
- Kastle-Meyer
- Leghemoglobin
- Legume
- Phenolphthalein
- Polymerase chain reaction
- Presumptive
- Short tandem repeats
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Genetics