A mixed DNA profile controversy revisited

Semaan et al. (J Forensic Res, 2020, 11, 453) discuss a mock case “where eight different individuals [P₁ through P₈] could not be excluded in a mixed DNA analysis. Even though … expert DNA mixture analysis software was used.” Two of these are the true donors. The LRs reported are incorrect due to the incorrect entry of propositions into LRmix Studio. This forced the software to account for most of the alleles as drop-in, resulting in LRs 60–70 orders of magnitude larger than expected. P₁, P₂, P₄, P₅, and P₈ can be manually excluded using peak heights. This has relevance when using LRmix which does not use peak heights. We extend the work using the same two reference genotypes who were the true contributors as Semaan et al. (J Forensic Res, 2020, 11, 453). We simulate three two-donor mixtures with peak heights using these two genotypes and analyze using STRmix?. For the simulated 1:1 mixture, one of the non-donors’ LRs supported him being a contributor when no conditioning was used. When considered in combination with any other potential donors (i.e., with conditioning), this non-donor was correctly eliminated. For the 3:1 mixture, all results correctly supported that the non-donors were not contributors. The low-template 4:1 mixture LRs with no conditioning showed support for all eight profiles as donors. However, the results from pair-wise conditioning showed that only the two ground truth donors had LRs supporting that they were contributors to the mixture. We recommend the use of peak heights and conditioning profiles, as this allows better sensitivity and specificity even when the persons share many alleles.     

Forensic Application of Analytical Mechanics in Fatal Fall From a Height

Fatal fall from a height initiated with a swinging motion on the sagittal plane of the victim's body is examined. Method of analytical mechanics is adopted to establish the functional relations between the swinging angle of the body and the force needed to sustain the body until release, and the amount of the horizontal displacement that would occur after release. The analysis is applied to support an expert opinion presented in a criminal court in which two accused were convicted of murder for dropping a female victim from a bridge. The results indicate that it is unlikely for the body to locate as recorded by the police investigation report in the case. This study demonstrates that a straightforward mechanical analysis can be utilized to examine uncommon falling scenarios.     

A conceptual replication of the Strategic Training Initiative in Community Supervision (STICS)

Objectives

This study was an attempt to replicate the findings from an earlier experimental evaluation of a probation officer training program by Bonta et al. (Criminal Justice and Behavior, 38: 1127–1148, 2011). An experimental design was used with an improvement in the random assignment of clients and was tested with a sample of probation officers from a new jurisdiction.

Methods

Probation officers from the Canadian province of Alberta were randomly assigned to training or probation-as-usual. Officer behavior was measured by audio recordings of supervision sessions and recidivism was defined as a new conviction within 2 years of the initial recording. Attrition resulted in 27 probation officers submitting audio recordings of supervision sessions over a 6-month period (15 in the experimental group and 12 in the control). There were 160 recordings of 81 probationers submitted.

Results

The audio recordings showed inconsistent changes in officer behavior and no differences in recidivism between the clients of the experimental and control probation officers. However, the use of cognitive techniques by the probation officers was associated with a longer time to recidivism. In addition, by 10 months, more than half of the trained officers stopped their involvement in ongoing professional development activities.

Conclusion

Although the study failed to replicate the major findings reported by Bonta et al., it did highlight the importance of cognitive techniques in officer training. The results are interpreted with respect to the replication literature and the difficulties inherent in direct and conceptual replications especially in real-world settings.

     

IDENTIFYING THE PSYCHOLOGICAL FACTORS THAT MEDIATE THE ASSOCIATION BETWEEN PARENTING PRACTICES AND DELINQUENCY*

Past research has largely ignored the developmental changes within the child that account for the association between parenting and risk for delinquency. We used structural equation modeling and data from a longitudinal study of several hundred African‐American families to test the contentions of various theories regarding the sociocognitive and emotional factors that mediate the impact of parental behavior on a youth's risk for delinquency. Our findings largely supported the theories. The impact of monitoring/discipline was indirect through low self‐control and acceptance of deviant norms, whereas the effect of hostility/ rejection was indirect through low self‐control, hostile view of relationships, and acceptance of deviant norms. These two dimensions of parenting were no longer related either to affiliation with deviant peers or to conduct problems once the effects of these psychological characteristics were taken into account; the impact of these parenting practices was completely mediated by these four cognitive/affective variables. Contrary to expectation, however, these psychological factors did not mediate any of the relationship between caretaker involvement in antisocial behavior and child conduct problems.