Summarize the Importance of funding mental health regarding mentally ill individuals in prison

Much has been written on the importance of taking care of prisoners' mental health, both while they are in the system and upon their release. Recidivism rates are greatly increased where prisoners are unsupported after they have been released from prison, with one contributing factor being that prisoners' mental health issues often go untreated.
Mental health funding is lacking in the general population, as well as the prison population, and taxpayers can often be loath to see their tax dollars being spent on the incarcerated. In the long run, however, studies show it benefits society to ensure that the mental health needs of offenders are met. In the UK, it was identified that suicide rates in prison have risen shortly over the past decade, and over 70% of suicides in prison are committed by inmates found to have mental health issues. This is an issue because prisoners' needs are also important. From a community perspective, however, perhaps the more pressing concern is the disproportionate number of mentally ill individuals who are both existent within the prison system and released, untreated, into the general population every year.
Studies have shown that close to 20% of those imprisoned in the United States have some form of mental health issue, far higher than that in the general population. There is, in many cases, a direct correlation between mental health issues and the commission of crimes. Numerous individuals are driven to crime by their untreated mental health needs. Where these individuals enter and then leave the prison population without having these needs addressed, the likelihood that they will once again be driven to crime by mental illness is high. The connection between violent crime and serious mental illness has been demonstrated again and again.
Often, "mental health issues" is interpreted to mean illnesses like schizophrenia and borderline personality disorder, which certainly can contribute to offending. However, the vast majority of mental health issues identified in prison are connected to drug and alcohol addiction, with a significant proportion of crimes being committed by those under the influence of these substances. As such, it is to the benefit of society to spend money on funding programs to help prisoners addicted to these substances. Where prisoners can be released from prison clean of their addictions, and can be offered ongoing support outside of the prison environment to remain clean, it is far less likely that they will relapse and commit further crimes under the influence of toxic substances. Put shortly, ongoing mental health support for ex-prisoners slashes recidivism rates.
It can be difficult to summon public support for any program involving offenders, or indeed involving mental illness. However, in this group, the connections between the two issues are starkly drawn and it is demonstrably to the benefit of society as a whole to ensure that the mental illnesses of prisoners, which correlate directly with an increased tendency to offend and reoffend, are dealt with both in prison and upon reintegration into society.
https://www.nao.org.uk/report/mental-health-in-prisons/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3793843/