Yusuke Otsuka

Japanese Interrogation Techniques From Prisoners’ Perspectives

This study examined responses to a self-report questionnaire on interviewing techniques administered to 291 incoming adult male prison inmates across Japan who were convicted of murder, robbery, arson, rape, forcible indecency, or kidnapping. The questionnaire focused on interrogations that led to confessions. Four interview styles (Evidence-confrontational, Relationship-focused, Undifferentiated-high, and Undifferentiated-low) were identified. For prisoners who had already decided to confess before their interrogation, interview styles had no effect on the tendency to confess. However, when prisoners were undecided about confessing or had previously decided to deny allegations, the Relationship-focused and Undifferentiated-high interview styles were associated with confessions. Furthermore, prisoners who experienced Relationship-focused interviews were more likely to provide previously undisclosed information to the police.

Multivariate Models for Behavioral Offender Profiling of Japanese Homicide

Although many studies have been conducted on behavioral profiling of homicide offenders, none of these have empirically shown that this technique has scientific validity and solid accuracy. Based on data from 839 Japanese homicide cases, we constructed multivariate logistic regression models to infer offenders’ characteristics of sex, age, stranger offender, criminal record, single offender, member of organized crime, and residential area. We evaluated validity with a tenfold cross-validation procedure and a receiver operating characteristic (ROC) analysis. The results indicated that the area under the ROC curve ranged from .70 to .87, suggesting moderate and sufficient accuracy. Such a multivariate approach would be useful to reduce costs and minimize errors in the early stages of an investigation, especially for jurisdictions that possess large homicide databases.

A Multivariate Model for Analyzing Crime Scene Information: Predicting Stranger, Solo Offender, and Money-Oriented Motive of Japanese Homicides

This study examines the validity of a statistical offender profiling technique that predicts the multi-dimensional classification of homicide offenders. Analyzing 539 Japanese homicide cases, we constructed multivariate prediction models that infer classifications defined by three dichotomous variables (stranger offender, solo offender, money-oriented motive) on the basis of crime scene information. We evaluated the validity of the models with a 10-fold cross-validation procedure and a receiver operating characteristic (ROC) analysis, and found the models to have moderate accuracy (area under the curve [AUC] = .73 to .82). We discussed the results from the perspective of the offender’s rational choices in the crime scene and crime specialization.

Police Officers’ Ability to Detect Lies Within a Deception Paradigm

This study aimed to examine police officers’ accuracy in classifying guilty and innocent participants using 3 interviewing styles (evidence-focused, relationship-focused, and control). In a modified version of Russano, Meissner, Narchet, and Kassin’s (2005) deception paradigm, participants who had violated a rule (i.e., cheating while solving problems) were considered guilty, whereas those who had followed the rule were considered innocent. After interviewing 234 adult men, 11 experienced male police officers accurately classified over 90% of them as guilty or innocent. Of 160 participants who did not admit to cheating, 140 (87.5%) were correctly classified. There was no statistically significant relationship between interviewing style and police officers’ identifications of guilty deniers (i.e., liars) and innocent deniers (truth tellers). However, interviewers were more likely to believe guilty deniers in the evidence-focused condition, and they tended to believe innocent deniers in the relationship-focused condition. These findings suggest that the ability to detect deception might be influenced by interviewing style.

Effects of Rapport Building on Confessions in an Experimental Paradigm.

Recently, several studies in Western countries have experimentally investigated interviewing techniques designed to elicit true confessions from guilty suspects and to minimize false confessions by innocent suspects. This study was the first to explore these issues in Japan, with special focus on a rapport-based approach using a modified version of the experimental paradigm devised by Russano, Meissner, Narchet, and Kassin (2005). Experienced police officers interviewed 234 20- to 50-year-old male participants to ascertain whether they broke an experimental rule during a problem-solving session. Among 114 guilty participants (i.e., those who broke the experimental rule), 74 confessed to cheating, whereas none of the innocent participants (i.e., those who did not break the rule even though a confederate attempted to get them to do so) falsely confessed. Further analyses showed that guilty participants who were interviewed using a relationship-focused approach that emphasized rapport building were more likely to confess than those in a control condition; the presence of a camera had no effect on the difference between the 2 interview conditions. Furthermore, there were no significant interviewing style differences in the participants’ perceptions of fairness or suggestiveness.

Practice of offender profiling in Japan

The main aim of this study was to determine the current situation of offender profiling in Japan. In addition, the accuracy of crime linkage and inferring offenders’ profiles were examined. To evaluate offender profiling comprehensively, we conducted a national survey of 156 people responsible for offender profiling between 2011 and 2012 to obtain their demographic characteristics and experience related to profiling. Furthermore, we also used a sample of 296 resolved cases to examine the content of profiling and the accuracy of predictions in offender profiling. The results of the statistical analyses revealed that police professionals from various backgrounds were engaged in profiling in Japan; 76% were police investigators, and 19% were professionals at forensic science laboratories engaged in psychological work. Regarding the utilization of profiling results in police investigations, 46% of profiling ‘led to identification of offender’. As for prediction accuracy, the rate of linkage errors (i.e. where profilers could not correctly link incidents even when they knew of the occurrence of these incidents) was 15%. Accurately inferring an offender’s profile was found to be between 72% (means of transportation) and 100% (sex). We also discussed the challenges faced by the police who practise offender profiling in Japan.