Summary: A new study finds that violence within Italian mafia groups spreads in a contagious way: individuals who commit violent acts together are far more likely to carry out further violence than those who act alone.
Researchers analyzed the criminal careers of 9,819 people convicted of organized crime and report that prior violent co-offending substantially increases the probability of future violent behaviour. The pattern points to group dynamics—shared responsibility, social pressures, and collective justifications—that normalize and sustain violent acts within mafia networks.
These findings highlight the complex social mechanisms that fuel organized-crime violence and suggest that interventions targeting group processes could be essential for reducing future offences.
Key facts
- Those involved in violent co-offending are more than three times as likely to commit future violent offences compared with solo offenders.
- The study examined data on 9,819 organized-crime convicts and found a persistent, long-lasting influence of past violence on later behaviour.
- Among mafia members in the data set, violent co-offending occurred about four times more often than violent solo offending, underscoring the central role of group interactions in spreading violence.
Source: University of Exeter
Violence spreads contagiously within Italian mafia groups, new research shows.
The study shows that committing violent crimes as part of a group increases the likelihood that individuals will continue to commit violent offences, compared with those whose past violence was committed alone. Prior violent co-offending exerts a stronger influence on future violence than prior violent solo offending.
Specifically, individuals who committed violent acts with others were 14.2 percentage points more likely to commit another violent offence in the next observed period, while those whose violence was committed alone were 4.9 percentage points more likely to re-offend. A violent first offence, earlier onset of criminal activity, and younger age also raised the probability of subsequent violence.
The research was led by Cecilia Meneghini (University of Exeter) and Francesco Calderoni (Università Cattolica del Sacro Cuore and Transcrime), using specially authorized data from the Italian Ministry of Justice covering 9,819 individuals linked to organized crime and 178,427 final convictions. The dataset records the year of each crime, its type, and whether it was committed with others.
The offender cohort spans births from 1927 to 1994, with more than 80% born between 1950 and 1980; the earliest recorded offence in the data is from 1964 and the most recent from 2016. Of the 9,819 offenders, 173 were women. Violent offences were defined to include assault and violent offences, murder, and robbery.
Dr Meneghini explained that the presence of other people matters for how mafia members behave: group settings can encourage escalation. “The dynamics of violence spread around the mafia like a contagion,” she said. Group interactions may provoke members to egg each other on, lower individual inhibitions, and provide moral rationalizations that make violence easier to sustain over time.
Dr Calderoni emphasized that collective violent acts have a stronger effect on later violence than solo violent acts. While past group violence raises the chance of future group violence, it does not predict future solo violent acts—indicating that the transmission of violence operates primarily through group-based mechanisms rather than simple internalization by individuals.
The researchers argue mafia membership creates a social environment that promotes co-offending. Joining such groups alters an individual’s social status, obligations, and relationships in ways that support cooperative criminal acts—especially violent cooperation, which often serves practical and symbolic functions within criminal organizations.
About this social behaviour and violence research news
Author: Louise Vennells
Source: University of Exeter
Contact: Louise Vennells – University of Exeter
Image: Image credited to Neuroscience News
Original research: Open access. Title: “Co-offending and the Persistence of Violence: A Dynamic Analysis” by Cecilia Meneghini et al., Journal of Quantitative Criminology.
Abstract
Co-offending and the Persistence of Violence: A Dynamic Analysis
Objectives
Past studies have linked prior violent co-offending to later violence via a social contagion mechanism, but they often ignore the full span of criminal careers and the various group dynamics at play. This study investigates the long-term effects of prior violent solo and co-offending on later individual violent behaviour among Italian organized-crime offenders.
Methods
Using career data from 9,819 offenders, the authors model offending choices as a discrete-time Markov process and apply dynamic random-effects probit models to estimate how prior violent solo and co-offending affect future violence, controlling for confounders and unobserved individual differences.
Results
Violence is persistent among organized-crime offenders. Prior violent co-offending has a larger effect on future violent behaviour than prior violent solo offending. Prior co-offending increases the likelihood of future co-offending but does not predict future solo violent acts.
Conclusions
The findings indicate that co-offending facilitates the spread of violence within criminal groups through self-sustaining group dynamics rather than through a simple internalization of violent behaviour by individuals. Although limited individual-level data constrain interpretation, results suggest violence transmission is driven more by group effects than by the characteristics of individual co-offenders.