Rossmo's Criminal Investigative Failures
Chapter 7 - Narrative: Judgment, Heuristics, and Biases in Criminal Investigations
David and Nelson Stubbins
This chapter on the necessity for investigators to form theories of how crimes were perpetrated (narratives) and the trappings of heuristics (cognitive shortcuts) which are required in quick decision-making is a must read for all of us wishing to practice clear thinking to achieve optimal conclusions.
The authors are a psychologist and professional in organizational development respectively. Their chapter begins with the oft cited sailors' warning, "Hic Sunt Dracones"... Here Be Dragons, which even Disney's Captain Barbosa offers as a logical explanation for the unknown, at a loss to provide any other rational conclusion.
Cap'n Barbosa. Or as we call him, Bardolino Barolo Barbera Barbosa
Yesterday I was trying to explain to my daughters the fallacy of this type of reasoning. We have begun a project of cataloguing money we find in the street as a method to teach them about statistics and probability. I had noted that thus far I had found the most money (16 cents) while going out for morning jogs. This led one of them to the conclusion that joggers must be better finders of money. It was certainly an explanation, but not the best one. Jogging did not imply finding money; the fact that I had covered more ground then them while out for 4 miles each day was perhaps the better fit (Correlation without causation). Still, we've done this for a week: we need more data. And we have to be open to all sorts of ideas and creative thinking (maybe dragons, but let's keep looking).
The problem of course in real life is that investigators don't have the luxury of time afforded formal research studies. They have to use heuristic techniques to find sometimes the "best fit" for a theory when a full-proof, irrefutable conclusion can't be found. This can lead to errors, at the worst it can lead to false accusations and convictions.
Narrative mistakes come to mind when I consider my sister, Theresa's investigation. Despite evidence to the contrary, initial investigators focused on an idee fix of a drug overdose and conspiracy / cover-up by student friends of the victim. From this point all evidence that supported that theory was considered (drugs on campus, no apparent violence to the victim), and anything working to dis-confirm it was discarded (the victim was not a habitual drug user, the way in which the victim was found was more indicative of a sex crime). Confirmation bias continued as investigators made the decision to focus their interviews almost exclusively on students (of 200 witness statements, close to 180 were from students). When the investigation reached a dead end, investigators did not go back and re-scrutinize their narrative with logic and analysis; instead they followed what appeared logical for their theory to fit: Wait... in time one of the student conspirators will crack and come forward.
Corporal Roch Gaudreault (right) at the scene of the crime, 1978
25 years later when two investigators who worked on the original case were questioned, their first responses were very different and telling. Private detective, Robert Beullac was careful to state, "well there were two theories, one of a drug overdose and one of a serial sexual predator" The officer for the Surete du Quebec, the official investigating police force, Corporal Roch Gaudreault was much more definite in his response: "I am still convinced of a drug overdose".
As the authors state, "Once a story starts to form, it is increasingly more difficult to step back and see how alternative narratives also explain the evidence." This idea is beautifully articulated in chapter 8 of Criminal Investigative Failures, Who Killed Stephanie Crowe? a case-study documenting the and tunnel-visioning of the Escondido Police Department into thinking a group of boys (including the victim's teenage brother) conspired to murder a 12-year-old girl in the face of conclusive evidence that she was murdered by a local drifter. The story is particularly galling in light of testimony by FBI Senior Special Agent Mary Ellen O'Toole in support of the Escondido theory in which specific forensic blood evidence against the drifter was deemed "irrelevant" by O'Toole. One wonders how author Gregg O. McCrary, a former FBI agent who provided expert witness testimony against Escondido, managed not to blow his top in the face of such a textbook case of bureaucratic narrow-mindedness and groupthink.
FBI SSA Mary Ellen O'Toole
Consider this. The name of this website is "Who Killed Theresa", yet the chapter in Criminal Investigative Failures is entitled, "What Happened To Theresa Allore". The change in title was a well thought out consideration by editor Kim Rossmo. We don't know what happened to Theresa. Maybe she did commit suicide or was involved in some drug conspiracy. Maybe the evidence that would confirm those stories has been lost. Circumstantial evidence points to a theory that she was sexually assaulted and murdered, like two other young girls in that region at that time, but there is no conclusive evidence.
Private detective, Robert Buellac (now deceased)
Yes, I play more to this theory, but that has to do with some personal motivations more than bias. Theresa suffered enough humiliations through bias and poor vetting, I am not willing to let those humiliations continue without conclusive evidence. But I am always open to the one narrative that will best fit all the evidence and finally allow this mystery its full and proper resolution.
posted by John Allore @ 1/12/2009 12:01:00 AM
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