According to Wikipedia South Africa has 240 prisons of various sorts (for men, women, both sexes and children) with about 190 000 prisoners and 34 000 staff. That works out at an average of about 790 prisoners per prison and about 142 staff members per prison and about one staff member for every 6 prisoners, at a budgeted cost in 2012 of about 17.9 Billion Rands, an average of about R94 210 per prisoner for 2012 alone. If we then add the police and judicial services (R65b and R15.1b) that comes to R98 billion or an average per prisoner of about R516 000 per prisoner per year. Surely that says something about crime not paying society. Then of course there is the question about the adequacy of the prison service, the corruption within its ranks, its inability to cope with the sheer volumes of inmates it is responsible for and the levels of arrest, conviction, rehabilitation and recidivism (re-offenders).
It is generally accepted that it costs less to provide a full degree than it does to house a prisoner for one year. With numbers like those above, this is easily believable. It is also a matter of common sense that an individual who is educated and skilled and employed is less likely to be drawn into criminal activity than an individual who is un-skilled, uneducated and unemployed. It is also generally accepted that the surest way of directing a young offender into a life of criminality is to sentence him or her to time in a correctional facility.