Deceptive 911 callers in homicide investigations are a crucial challenge for law enforcement. Callers who report emergencies while concealing their involvement in a crime can mislead investigators, delaying justice and diverting resources. To aid in detecting caller involvement in the emergencies that they report, the Considering Offender Probability in Statements (COPS) Scale was developed as a checklist for evaluating 911 callers’ speech and behavior (Harpster et al., 2009). Marketed as a valuable tool for law enforcement, it has been used to train officers and sold as a method for identifying innocence or guilt among callers in homicide cases. However, new research from the Federal Bureau of Investigation (FBI) and Villanova University raises serious concerns about its effectiveness.
The FBI’s Behavioral Analysis Unit evaluated the COPS Scale, testing its reliability in real-world settings and its impact on potential interview questions (O’Donnell et al., 2025). Sworn law enforcement officers applied the scale to analyze 911 calls in homicide and suicide investigations, assessing whether its behavioral indicators could reliably differentiate innocent from guilty callers. The results revealed that calls were misclassified over 40% of the time. Many of the scale’s indicators were not useful in discriminating between call types, and some of the most influential “guilt indicators” were actually more common among innocent callers. Further, judgments of caller involvement also influenced the nature of potential interview questions subsequently asked by law enforcement. The results of this study suggest that the scale should not be used in actual investigations to evaluate callers’ potential innocence or guilt.
Expanding on these concerns, Patrick Markey and his team at Villanova University conducted an independent analysis of the COPS Scale (Markey et al., 2025). They examined whether the scale’s total score—based on the number of “guilty indicators” a caller exhibited—could reliably distinguish deceptive from truthful callers. Their findings reinforced the FBI’s conclusions: The COPS Scale failed to differentiate between guilty and innocent callers. Many of its core assumptions, such as the belief that deceptive callers avoid urgency or are unemotional, did not hold up under scrutiny. A comparison of effect sizes from prior research revealed that studies conducted by the authors of the COPS Scale reported much stronger results than the independent replications did, raising concerns about the scale’s scientific rigor. The inconsistencies in the study results highlight the risks of relying on deception detection tools that have not been independently validated, especially when their use can shape investigations and influence life-altering decisions.
The FBI (O’Donnell et al., 2025) and Villanova (Markey et al., 2025) studies provide compelling evidence that the COPS Scale is not a valid tool for detecting the innocence or guilt of people placing 911 homicide calls. Although law enforcement officers are routinely faced with the challenge of detecting deception, using a tool that does not have sufficient validation could have severe consequences, including wrongful suspicion of innocent individuals and waste of investigative resources. The results of these studies underscore the importance of establishing independent scientific validation before adopting forensic tools in real-world investigations. Flawed deception detection methods not only risk ineffective policing but also can lead to serious miscarriages of justice, undermining investigations and damaging the integrity of the criminal justice system.