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Author Spotlight: Diatom Testing for Forensic Drowning Examination
Published on: November 10, 2023
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Comparative study on diatom morphology and molecular identification in drowning cases
Mengyan Liu1, Yi Zhao2, Yuzhe Sun3
1Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China; Forensic Judicial Appraisal Center of Beijing Public Security Bureau, Beijing, 100192, China.
Forensic Science International
|November 4, 2020
Summary
Forensic diatom detection aids drowning investigations. Microscopic and DNA methods show limitations, with microscopy yielding higher positive rates but a robust DNA database being crucial for accurate drowning cause determination.
Area of Science:
- Forensic Science
- Microbiology
- Genetics
Background:
- Determining drowning as the cause of death in submerged bodies is critical for criminal investigations.
- Diatom detection in human organs is a key method for identifying drowning.
- Current morphological and molecular diatom detection methods have limitations.
Purpose of the Study:
- To compare the reliability of diatom morphological identification and DNA metabarcoding for drowning forensics.
- To evaluate the effectiveness of different DNA barcodes (BacirbcL vs. 18S605) and internal organs for diatom detection.
Main Methods:
- Collected 79 samples from 23 victims in 19 known drowning cases.
- Performed microscopic observation for diatom morphology.
- Utilized DNA metabarcoding with two different barcodes (BacirbcL and 18S605).
Main Results:
- Microscopic observation yielded higher positive diatom detection rates (kidney: 52.6%, liver: 26.3%, lung: 58.8%) than DNA metabarcoding (kidney: 31.6%, liver: 31.6%, lung: 35.3%).
- Barcode 18S605 detected more diatoms than BacirbcL, but BacirbcL aligned better with environmental samples.
- Microscopic and DNA barcoding results showed low correlation; no significant difference in diatom enrichment across tested organs.
Conclusions:
- Current DNA barcode reference sequences are insufficient and contain errors, limiting molecular identification accuracy in drowning forensics.
- Microscopic identification currently shows a higher success rate than molecular methods due to database limitations.
- Developing a reliable diatom DNA barcode reference database is essential for advancing molecular forensic techniques in drowning investigations.
