Unit 1 forensics

general logic of forensic identification

compare the crime scene evidence to a known sample

decide whether to exclude or include the suspect

A scientifically strong method requires

reliable data

objective criteria

known error rates

compared results between different examiners

why bitemark methods fall short

less information compared to other forensic methods

stretching of the skin affects accuracy

lack of standardization in analysis methods

multiple possible methods with no “gold standard”

broader lessons

forensic methods need strong evidence to show scientific validity

courts should demand scientific testing before admitting evidence

future forensic techniques must be tested early, transparently, and with known error rates

lawyers and judges must be more critical of expert testimony

bitemark identification may be headed toward scientific exclusion

current status

bite evidence remains debated in many jurisdictions

its use and reliability are frequently questioned

there are calls for it to end

problems with bitemark identification

compares bite marks on skin to a suspects teeth

used in courts for decades but now is facing strong criticism

some convictions based on bitemark evidence later exonerated by DNA testing

many experts consider it amoung the weakest forensic methods still in use

how it became accepted

courts admitted expert testimony due to bitemark rather than because of strong scientific backing

survived legal challenges even after new court rules requiring judges to assess scientific reliability

courts rarely challenged assumption underlying bitemark identification

key scientific concerns

skin is elastic, distorts easily, is a poor medium for preserving bite marks, and may not preserve fine bite marks

lack of empirical validation:national academy of sciences concluded in 2009 that bitemark identification lacks empirical evaluation

expert disagreement: experts often disagree with each other when analyzing the same bite marks/sometimes disagree with their own conclusions

standardization issues: mo standardized rules for declaring a ‘match‘ / multiple possible conclusions (ex digital overlay and comparison)

research findings: few rigorous scientific studies conducted / ealiers claims (uniqueness of teeth) not supported by new scientific evidence/research shows high error rates and frequent false positives