By Christopher Halkides
Main Factor leading to a wrongful conviction
Confirmation bias: One laboratory claimed to find ethylene glycol even though its retention time (the period it takes for a compound to traverse a GC column) was not identical to a standard sample of ethylene glycol. Another laboratory did not even bother to run a standard. One laboratory did not calculate that Ryan would have had to consume 300 liters of ethylene glycol to account for the results of the chemical analysis
Ineffective assistance of counsel: Ms. Stallings first attorney failed to present the possibility that Ryan suffered from a metabolic disorder, but the judge may have also circumscribed the defense.
Limitations of the analytical methods: More modern methods of chemical analysis are less prone to misidentification of compounds.
Synopsis of the Patricia Stallings case
Missourian Patricia Stallings was convicted of murdering her infant son Ryan by poisoning him with ethylene glycol. At least four separate samples of evidence showed the presence of ethylene glycol by gas chromatography (GC). Her second son David showed similar symptoms to Ryan’s and was found to have a rare metabolic disorder called methylmalonic acidemia (MMA). After a biochemist became interested in the case, he and others were able to show that Ryan also had MMA, and the compound identified as ethylene glycol was shown to be propionic acid instead.
Additional take-home messages
This case shows that private citizens can make a difference, but only when they are in possession of the facts. The biochemist who became interested only heard about the case from an episode of “Unsolved Mysteries.” This is one wrongful conviction in which neither the police nor prosecutor committed any ethical improprieties.