Take care in the community.

A quick check shows that there were 765 homicides in England and Wales in 2005/06 (April-March).
Turning to the BBC's preview of the Appleby report:
249 people have been killed by psychiatric patients released into the community over the last five years. So that's (if we average) 1 in 15 murders (c50 per year) committed by a released psychiatric patient.
Turning to the Home Office Statistical Bulletins:the average two year reoffending rate for those commiting crimes of violence is about 46%.

As shown in Figure 8, p9 of Re-offending of adults: results from the 2003 cohort, re-offending rates are lower among offenders discharged from a custodial sentence of at least a year (49 per cent) than among those discharged from a shorter custodial sentence (70 per cent). Some offender characteristics of those discharged from longer custodial sentences are associated with lower re-offending, including being older, having fewer previous convictions, and the offence types they were convicted for.
Disentangling the effect on re-offending of offender characteristics and the effect of the
disposal itself is difficult. One approach is to examine the difference between the actual rate
of re-offending and the predicted rate of re-offending, which is calculated solely using
offender characteristics. This suggests that custodial sentences of at least a year are more
effective in reducing re-offending. However, more detailed analysis is required to fully answer
this question and a research programme to that effect is currently being carried out.

Back to the report.

The report, entitled Avoidable Deaths, will reveal that one in six deaths were blamed on the failure to ensure patients took their medication properly.

So, does incarceration reduce crime?
I think so. But I'll have to work at this a bit harder. In the meanwhile I'll refer you back to what I said a few days ago (with apologies for the repetition).

Preamble. We on the right tend to believe in the imperfection of man. We don't believe (with Rousseau) in the noble savage (if he did), indeed we believe that, along with his life, he himself was probably nasty, brutish and short. We note with no surprise whatsoever that some modern archeology has estimated that in the past 25% of males died at the hands of others. We are not in the least taken aback to learn that "the great majority of Aboriginal people themselves are voting with their feet and assimilating into white society." In short, we think that civilization can do better.
I should add that Dalrymple writes very well about this (did I say he's good?)...
First main point. How is man improved from his state of innocent imperfection? By teaching, training, example and punishment.
We learn to care for others and treat them with respect by a mixture of experience (I banged my head, it hurt), observation (when I pinch little Jemima, she hurts like me), punishment (I hit little Jemima and I was smacked) and example (Jemima forebore to hit me and got a sweet). Much of this was (in the past) provided by good, or even fairly average parents. They were strongly encouraged in this task by society's approbation, encouragement and the threat of sanction.
The Golden Rule was commonly taught and widely understood as a recipe for a good society.

Second point. Where parents and the immediate environment fail, and occasionally they will, the wider society needs to be seen to step in. A process must be initiated which will rigorously attempt to establish the facts [and it's not a game]. If a transgression is established to have taken place then the process must impose punishment.
The purpose of punishment is threefold: to signal to the individual society's disapproval; to signal to society the fact that transgression will not go unpunished; to exact retribution and enable the individual to regard the transgression as "spent" so that they may be rehabilitated. In the interests of these purposes, other consideration of circumstances must take place and should affect the level and nature of the punishment.

Third point. It's much easier and more effective to run such a system with very limited chances to be `let off'. I.e. at most one warning should be given before a full punishment takes place and even minor transgressions need to be noticed else more serious ones will follow. In the language of parenting, "we need clear boundaries, which are firmly adhered to".

Fourth point. No system is perfect. We say with Flaubert [for we never despise wisdom, whatever the source] "perfection is the enemy of the good". Thus, to spell it out for the dullards, society will fail (if you like to put it that way). Some people will become hardened in their wickedness whom a different system might have saved. We accept this as the cost of imperfection. The alternative costs are even worse since they will penalise the innocent.

Final point. Look around you. Do you see any of this sort of thing happening? No, we see someone with 102 convictions being considered for parole rather than being required to serve his whole sentence. We see the prison population climbing fast in the UK despite more and more attempts to restrict imprisonment to fewer and fewer crimes (recorded crime 1 per 360 individuals per annum in 1921, 1 per 10 individuals per annum in 2001; 1 in 3,400 in prison in 1921, 1 in 850 in prison in 1999).

This last is a common phenomenon across Western civilization. And this Theodore Dalrymple has written a lot about (did I say he has a beautiful prose style?). This is what is available to anyone with a brain, the power of observation and the courage to believe that their current perfection may not be entirely due to their own efforts or the state of [no doubt secular] grace in which they were born.

Enough already.