Scenario 5: improvised explosive device material is found in an apartment. The only witness to activity there is an alcoholic in withdrawal.

Fire and rescue personnel respond to an explosion and subsequent fire in an apartment building near an industrial section of the city. Arson investigators determine the cause and origin to be detonation of an improvised explosive device (IED) in a backpack near or on the one deceased victim. Investigators found evidence that the detonated IED, and other unrecovered IED's, were constructed in the apartment. Documents have also been recovered that indicate that the resident of the apartment recently received inpatient treatment at a mental health facility in a neighboring state. A neighborhood canvas located one witness who observed several males in their early- to mid-20's carrying backpacks leave the residence yesterday. The witness could not further describe the individuals, stating that he only observed the people for a short period of time and did not pay close attention to them. Their automobile may have been parked on the street but the witness cannot be certain. The witness lives on the street and is in alcohol withdrawal, having been unable to obtain alcohol in the past 48 hours.

Problem: How can law enforcement facilitate good reporting from individual citizens, including those who might usually provide unreliable information (e.g., distressed homeless persons, people who were inebriated when they saw the event)?

Strategies: Memories often exhibit what is called "state dependency." That is, if an event is perceived while someone is under the influence of a drug (e.g., alcohol), then it is remembered better if the recall occurs under the same state (that is, while drinking). A similar effect sometimes has been found to operate for moods--that is, memories also are recalled better if the person is in the same mood they were in when they acquired the memory. This poses a potential problem for effectively interviewing people with histories of the abuse of alcohol or other drugs.

Problem: Can we identify the likely characteristics of suicide bombers in the Middle East at present, ask how many of the same characteristics (especially, support structures) might or do exist in the United States, and use these characteristics to identify people who might be considered at risk? Similarly, can we use what is known about the men who engaged in the attacks on the United States on 9/11, to offer a likely description of such a terrorist?

Strategies: Data mining techniques might be useful here. The data mining technique is useful when someone is confronted with a huge collection of individual items (e.g., telephone call narratives, case histories, medical histories, indices of aberrant behavior) and needs these items be prioritized according to which should be pursued thoroughly. It also allows the user to find patterns of behavior that are almost impossible for the human observer to perceive. Importantly, then, this is not just a technique that is faster than a human. It is a technique that allows a human to view aspects of a large data set that they otherwise would not be able to see, and to discover interesting associations ...