Summary
Aim
To investigate whether the crimes committed by offenders early in their criminal careers change in severity over consecutive offence episodes.
Method
Offence seriousness was measured across conviction episodes for a cohort of people born in NSW in 1994. We examined the relationship between offence seriousness and conviction episodes using two techniques. The first analysis involved stratifying offenders by total number of episodes and then using non-parametric tests to compare offence seriousness between and across episodes. The second analysis involved using group based trajectory modelling to investigate if there were groups of offenders who had different trajectories of offence seriousness over their first three conviction episodes.
Results
Across all offenders, non-parametric tests showed no consistent relationship between offence seriousness and conviction episode. In contrast, group based trajectory modelling provided evidence for four offence seriousness trajectory groups:
(1) an escalating group (16.1% of sample),
(2) a low stable group (32.7% of sample),
(3) a high stable group (26.0% of sample), and
(4) a de-escalating group (25.2% of sample).
Conclusion
Group based trajectory modelling provided evidence that the relationship between offence seriousness and conviction episodes varies for sub-groups of offenders. Potential implications for understanding and informing the prevention of serious crime are highlighted. Limitations of this study and challenges for future research are discussed.