Comparative Analysis of Violent Crime Statistics in Korea by Mental Illness Status (2012–2022): Implications of Deinstitutionalization

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Psychiatry Investig. 2025;22(6):612-619

Publication date (electronic) : 2025 June 16

doi : https://doi.org/10.30773/pi.2024.0309

Cheol Park^1,2, Ju-Yeon Lee¹, Jae-Min Kim¹, Il-Seon Shin¹, Seunghyong Ryu^,1, Sung-Wan Kim^,1,3

¹Department of Psychiatry, Chonnam National University Medical School, Gwangju, Republic of Korea

²Peace & Harmony Psychiatry Clinic, Gwangju, Republic of Korea

³Mindlink, Gwangju Bukgu Community Mental Health Center, Gwangju, Republic of Korea

Correspondence: Seunghyong Ryu, MD Department of Psychiatry, Chonnam National University Medical School, 160 Baekseo-ro, Dong-gu, Gwangju 61469, Republic of Korea Tel: +82-62-220-6148, Fax: +82-62-225-2351, E-mail: ryush@chonnam.ac.kr

Correspondence: Sung-Wan Kim, MD, PhD Department of Psychiatry, Chonnam National University Medical School, 160 Baekseo-ro, Dong-gu, Gwangju 61469, Republic of Korea Tel: +82-62-220-6148, Fax: +82-62-225-2351, E-mail: swkim@chonnam.ac.kr

Received 2024 October 12; Revised 2025 January 7; Accepted 2025 March 21.

Abstract

INTRODUCTION

Most individuals with mental illness who are receiving treatment are not violent and are more likely to be victims of crime than perpetrators [1-3]. However, certain factors can increase the risk of violent behavior, particularly in individuals with substance use disorders, untreated psychosis, or inadequate access to mental health care [4-6]. Active uncontrolled symptoms such as hallucinations and delusions are strongly associated with an increased risk of violence [5]. Moreover, comorbid substance use disorders significantly amplify the likelihood of criminal behavior [6,7]. As mental health services increasingly shift toward community-based care and reduce inpatient treatment options, the risk of criminal behavior among those with untreated or poorly managed mental illness may grow.

In recent years, concerns have been raised about the potential link between mental illness and criminal behavior, particularly violent crime, in the context of deinstitutionalization policies. Deinstitutionalization, a global movement aimed at reducing the number of psychiatric inpatients, has led to a transition from long-term hospitalization to community-based treatment. While this shift promotes personal autonomy and human rights, inadequate support and resources can lead to adverse outcomes, including the criminalization of individuals with mental illness. In the United States, deinstitutionalization began in the mid-20th century. It accelerated during the 1960s and 1970s, contributing to increased rates of violence and a subsequent rise in arrest and incarceration rates among people with mental illness in communities [8-10].

In South Korea, the Mental Health Welfare Act was amended in 2017 to make compulsory hospitalization more difficult. Following this policy change, psychiatric closed wards increased from 56,839 in 2012 to 67,845 in 2016 but then declined to 59,267 in 2022 [11]. An unintended consequence is that individuals with untreated or poorly managed mental illness in communities may become more vulnerable to involvement in violent crime, as seen in Western countries. This highlights the need for more comprehensive mental health policies that ensure access to appropriate care and address the potential for criminalization.

This study contributes to this ongoing discussion by analyzing violent crime statistics in South Korea between 2012 and 2022, comparing individuals with mental illness to those without. By examining data before and after the 2017 amendments to the Mental Health and Welfare Act, we aim to explore whether deinstitutionalization has influenced violent crime rates among individuals with mental illness and what this implies for mental health and criminal justice policies moving forward.

METHODS

RESULTS

Figure 1 shows the trends from 2012 to 2022 in the number of offenders with or without mental illness in serious violent crimes. Across all crime types, the trend in the number of offenders with mental illness seems to have continued without significant change before and after 2017. However, for robbery and arson, the trend in the number of offenders without mental illness has been steadily decreasing. Consequently, the proportion of offenders with mental illness relative to the total number of offenders in robbery and arson has increased since 2017 (Figure 2).

Figure 1.

Trends in serious violent crimes committed by offenders with and without mental illness (2012–2022). The y-axis indicates the number of offenders each year divided by the number of offenders in 2017, the year the Mental Health and Welfare Act was amended. The solid line represents the trends for offenders with mental illness, while the dashed line shows the trends for offenders without mental illness.

Figure 2.

Proportions of offenders with mental illness among the total number of offenders in serious violent crimes and other violent crimes (2012–2022). The y-axis indicates the proportions (%) calculated as (number of offenders with mental illness)/(number of offenders with mental illness+number of offenders without mental illness)×100 for each crime type.

Our analyses comparing the mental state of offenders involved in crimes between the 2012–2016 and 2018–2022 periods revealed mixed findings across different crime categories (Table 1). For murder and attempted murder, there was no significant difference in the number of offenders with or without mental illness between the two periods, indicating that the proportion of offenders with mental illness remained stable (χ²=0.01, p=0.980). In contrast, robbery showed a statistically significant difference between the two periods, primarily due to a larger decrease in offenders without mental illness compared to those with mental illness (χ²=11.92, p=0.001). Consequently, the proportion of offenders with mental illness among total robberies increased from 2.3% to 3.3%. In sex offenses, there was also a statistically significant difference, with the number of offenders without mental illness increasing while those with mental illness showed a slight decrease (χ²=23.68, p<0.001). The proportion of sex offenses committed by individuals with mental illness decreased from 4.2% to 3.6% of total sex offenders. Arson also demonstrated a significant difference between the two periods, with notable shifts in both groups, particularly an increase in offenders with mental illness, resulting in their proportion rising from 17.3% to 21.7% of total arson cases (χ²=19.90, p<0.001) (Table 1).

Table 1.

Comparison of crime numbers and proportions by mental illness status (2012–2022)

Figure 3 demonstrates the trends from 2012 to 2022 in the number of offenders with or without mental illness in other violent crimes. For assault and battery cases, the number of offenders without a mental illness has been slowly decreasing before and after 2017, while the number of offenders with a mental illness has remained largely unchanged. For other violent crimes, such as confinement and extortion, threats and blackmail, and vandalism, both the number of offenders without and with mental illnesses continued to increase before and after 2017, but the increase in the number of offenders with mental illnesses was particularly pronounced. Consequently, the proportion of offenders with mental illness among the total number of offenders in these other violent crimes has increased since 2017 (Figure 2).

Figure 3.

Trends in other violent crimes committed by offenders with and without mental illness (2012–2022). The y-axis indicates the number of offenders each year divided by the number of offenders in 2017, the year the Mental Health and Welfare Act was amended. The solid line represents the trends for offenders with mental illness, while the dashed line shows the trends for offenders without mental illness.

For assault and battery, a highly significant change was observed between the two periods, with a notable decrease in offenders without mental illness and a slight increase in offenders with mental illness (χ²=403.90, p<0.001). As a result, the proportion of offenders with mental illness among total assault and battery cases rose from 1.3% to 1.7%. Confinement and extortion exhibited a smaller but statistically significant difference, primarily due to an increase in offenders with mental illness (χ²=3.94, p=0.047). For threat and blackmail, a significant rise was observed in both groups with a particularly large increase among offenders with mental illness, leading to a rise in their proportion from 1.5% to 3.1% (χ²=192.64, p<0.001). Lastly, vandalism demonstrated a statistically significant difference between the periods, reflecting increases in both groups, especially among offenders with mental illness (χ²=97.85, p<0.001). Consequently, the proportion of offenders with mental illness in vandalism cases increased from 3.9% to 5.1% (Table 1).

DISCUSSION

The findings of this study reveal key differences in violent crime trends between individuals with and without mental illness over the past decade, with significant implications for mental health policies in Korea. Notably, a considerable shift in crime patterns emerged after the 2017 amendments to the Mental Health and Welfare Act, which made involuntary psychiatric hospitalization more difficult. Although the overall rates of violent crimes such as murder, attempted murder, and robbery have decreased, certain types of violent crimes—particularly arson, assault, and battery—have increased in numbers and proportion of total crimes among individuals with mental illness. As mental health policies increasingly prioritize outpatient treatment, ensuring that individuals with severe mental illness receive adequate care in community settings remains a significant challenge.

The trend of increasing other violent crimes among individuals with mental illness from 2018 to 2022 likely reflects broader societal consequences of deinstitutionalization without sufficient community-based support. This trend raises concerns about the consequences of deinstitutionalization, particularly as the reduction in psychiatric hospital beds has left many individuals with acute psychiatric conditions in the community without adequate support. Without sufficient mental health services, individuals with mental illness may be disproportionately vulnerable to engaging in certain types of violent crime, exacerbating their criminalization. This highlights the need for a reassessment of Korea’s mental health care infrastructure, particularly the availability of inpatient beds and comprehensive community-based services.

There has been a significant rise in arson cases among individuals with mental illness after 2017. This aligns with existing research linking arson to mental health issues [12-15], particularly among individuals experiencing cognitive and emotional dysregulation [16]. While fire rates, in general, have decreased in countries like the U.S. due to enhanced fire safety regulations and technologies [17], arson remains closely associated with impulsivity, emotional instability, and psychosis [18,19]. Studies, including those from Australia, have shown a high prevalence of mental illness among arsonists, reflecting a similar trend observed in Korea [20]. This increase in arson among the mentally ill suggests that the reduction in inpatient care may have left vulnerable individuals without the necessary interventions to prevent such behavior.

The overall number of serious violent crimes, such as murder and attempted murder, decreased in both groups. This suggests that general trends in violent crime reduction, likely driven by improved law enforcement techniques and societal changes, have consistently impacted both populations. However, the sharp increase in sex offence cases among individuals without mental illness, compared to stable rates among the mentally ill, suggests that broader societal factors, such as increased reporting during the #MeToo movement, have not equally affected both populations. The rapid spread of the #MeToo hashtag on social networking platforms led many women to share their experiences of sex offences and harassment, significantly increasing the demand for counseling services related to sexual violence [21-23]. This institutional shift has made it easier for victims to report incidents. Therefore, the rise in reported sex offense cases since 2018 may be likely attributable to an increase in the rate of reporting rather than a rise in the actual occurrence of such crimes. In contrast, the sex offense rates among individuals with mental illness, who tend to have less social interaction compared to the general population, were not as closely influenced by these societal reporting trends.

Robbery trends present a more complex picture. While robbery rates significantly declined among individuals without mental illness, the reduction was minimal for those with mental illness. This suggests that societal factors contributing to the decline in robbery, such as increased surveillance and the shift to cashless transactions [24], may not have benefited individuals with mental illness to the same extent. The limited decline in robberies and increase in the proportion of people with mental illness among total robberies may reflect broader issues in mental health care and social support, where individuals with mental illness may lack the awareness or capacity to adapt to these societal changes.

The analysis of other violent crimes further emphasizes the growing disparity between individuals with and without mental illness. While assault and battery cases declined among individuals without mental illness, they slightly increased in the mentally ill group. Since 2006, the overall number of assaults in South Korea has risen, potentially due to changes in crime reporting systems like the Crime Information Management System [25]. However, this study reveals a decreasing trend in assaults among the general population from 2012 to 2022, which contrasts with the slight increase in the mentally ill group. This, along with significant increases in other violent crimes—such as vandalism, confinement, and threats—indicates that individuals with mental illness may be increasingly involved in non-lethal violent crimes. The pronounced rise in vandalism and threats, in particular, points to the need for better community-based mental health interventions that address the underlying causes of these behaviors.

These findings highlight the complex interplay between mental health policies and crime trends. While deinstitutionalization has advanced human rights by reducing compulsory hospitalization, it may inadvertently increase the risk of violent crimes among individuals with mental illness, especially when community-based mental health services are insufficient [8,26-29]. Similar trends have been observed in European countries and the US, where reductions in psychiatric hospital beds have coincided with increases in forensic beds, supported housing placements, and prison populations [28,29]. In the US, severely limited access to non-forensic psychiatric inpatient care has been linked to heightened risks of violence, incarceration, homelessness, premature mortality, and suicide among patients with psychiatric disorders [29]. Our findings align with international research, showing an increase in crime rates among individuals with mental illness following reductions in psychiatric beds [8-10]. However, Australian studies revealed some differing trends: while the general homicide rate declined over 24 years, the proportion of murderers with severe mental illness doubled in the most recent 12 years compared to the earlier period [30]. These cross-national findings highlight the urgent need for targeted interventions to address the mental health needs of this population and mitigate their risk of involvement in criminal activity. Expanding access to treatment, improving early intervention, and providing enhanced support for individuals with severe mental illness are critical steps toward reducing both crime and the criminalization of mental illness in Korea [31].

This study has several limitations that should be considered when interpreting the results. First, relying on police-reported crime statistics may not fully capture the extent of violent crime, particularly for crimes that go unreported or are underreported, especially within marginalized communities, including individuals with mental illness. This potential underreporting could lead to underestimating crime rates in these groups. Second, the classification of mental illness by the National Police Agency may not always align with clinically validated diagnoses. The potential for misclassification and its impact on data interpretation must be carefully considered. This broad categorization may encompass a wide range of conditions, from severe mental illnesses to neurotic disorders. Third, although the study highlights changes in crime trends among individuals with mental illness following the 2017 amendments to the Mental Health and Welfare Act, multiple confounding factors and other societal changes beyond this legislation may also have contributed to these trends. For instance, economic conditions, such as a recession, may disproportionately impact individuals with mental illness, potentially increasing vulnerability to criminal behavior. Additionally, the COVID-19 pandemic may have exacerbated this trend by limiting access to mental health services and support systems. Furthermore, changes in policing strategies, prosecutorial practices, and sentencing trends in the criminal justice system could also influence crime rates. These societal factors, along with other unknown variables, should be considered when interpreting the findings of this study. Finally, the current study was unable to analyze repeat offenders due to the lack of detailed offender-level data. Research indicates that recidivism rates among individuals with mental illness are significantly higher than those in the general population [32,33]. Repeat offending may play a significant role in shaping crime trends among individuals with mental illness. To address these limitations, future studies could utilize longitudinal data or integrate mental health treatment records with criminal justice databases to better identify causality and crime patterns within this population.

In conclusion, while overall violent crime rates may be decreasing, the rising rates of certain crimes among individuals with mental illness indicate the need for more comprehensive mental health strategies in Korea. The unintended increase in violent crime within this population highlights the necessity of enhanced support for those at risk. This study underscores the importance of a balanced approach that ensures adequate mental health care in both inpatient and outpatient settings to prevent violent incidents driven by unmanaged symptoms. The Korean government should significantly invest in strengthening community mental health care infrastructure and improving hospital-based case management in outpatient departments. These efforts are crucial to ultimately advancing the human rights of individuals with mental illness and should guide future policy discussions on mental health reform in Korea.

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