Criminal Trajectories from Adolescence to Adulthood in an Ontario Sample of Offenders

The two goals of this study were to describe the criminal trajectories of the Toronto sample on the dimensions of rate, type, versatility, and severity and to estimate distinct (latent) trajectory groups using current techniques of group-based trajectory analysis. The sample comprised 378 Canadian male offenders whose criminal trajectories was tracked for an average of 12.1 years (SD = 3.0), from late childhood/early adolescence into adulthood. Their mean age at the time of the most recent follow-up (March 17, 2001) was 27.6 years. The results indicated that the sample incurred a total of 4,964 unique court contacts (M = 13.1, SD = 9.6). The average criminal career lasted for 8.4 years (SD= 4.5), from ages 15.5 years to 23.9 years. In terms of the criminal career dimensions, the rate of offending resembled the classic age-crime curve, peaking at age 17. The diversity level increased from ages 12 to 16 years, reached a plateau until age 20, and declined thereafter. The severity level peaked at about age 24. These findings suggests that the transition from adolescence to adulthood is characterized by a lower rate of offending but an increased involvement in a range of offences and in more serious offences. Four trajectory groups following distinct developmental courses were identified using a semi-parametric groupbased model: low rate (LR), moderate rate (MR), high rate, rapid descenders (HRRD), and high rate chronic (HRC). This result addresses the issue of heterogeneity in offending rates within the sample. The implications of these findings for further research and criminal justice policy are presented. 2 INTRODUCTION Drawing upon the notion of a criminal career, the two aims of the present study were: (1) to describe the criminal trajectories of the Toronto sample on the dimensions of rate, type, versatility, and severity and (2) to estimate distinct (latent) criminal trajectories using current techniques of group-based trajectory analysis (Nagin, 2005). Since Blumstein et al. (1986) published their seminal two-volume work on criminal careers, the criminal career paradigm (CCP) has dominated the criminology literature. With an emphasis on longitudinal methodology and sophisticated mathematical approaches to model criminal trajectories, the CCP has made significant contributions to elucidating the nature and pattern of crime over time (Piquero et al., 2003; Piquero et al., 2007). A criminal career is defined as “the longitudinal sequence of offending committed by an individual offender” (Blumstein et al., 1986, p. 12), that is characterized during a lifetime by three components: an initiation or onset, a termination or end, and a duration or career length (Blumstein et al., 1988). During their career, offenders may display changes and continuities in criminal activity on a variety of dimensions, including rate, type, timing, versatility, and severity. It is the pattern of transition and stability on these sorts of variables across different developmental periods as well as the underlying reasons for the observed patterns that is of interest to researchers, theoreticians, practitioners, and policy makers (Barnett et al., 1987). The CCP also implies that individual offenders vary on the dimensions of rate, type, severity, versatility, and so forth. The task for the CCP is to model the criminal offending data to take into account this inherent heterogeneity. Semi-parametric group-based trajectory analyses (Nagin, 2005) provide an ideal way to address this issue by estimating unobserved (latent) trajectory groups based on longitudinal rates of offending. Describing within-individual trajectories is of particular relevance to research on chronic offenders whose criminal career often begins at an early age and persists into adulthood. These individuals are known to account for a large amount of court contacts, commit serious violent offences, and pose the greatest challenge to the criminal justice system (Piquero et al., 2003). Understanding their criminal trajectories will facilitate the development of more effective criminal justice policies and treatment and rehabilitation programs. Yet surprisingly little research on criminal careers has been conducted in Canada. Our aim is to fill this research gap.