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.     

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.

     

The Impact of Court Delays on the Prosecutor and the Defendant: An Economic Analysis

One important aspect of the economic theory of criminal court delay is to understand how the prosecutor and the defendant make their decisions, and how these respond to changes in trial delay. If both parties jointly maximise expected utility, trial delay may increase or decrease the number of trials, depending upon the decision makers' attitudes towards risk. The main policy implication is that providing the criminal courts with more resources in the form of additional judges and court capacity may lengthen the trial queue rather than shorten it. This is a counterintuitive result contrary to popular belief.