Thinking about Venables, sequestered in a closed unit for ten years, not possibly fully cognizant of the heinousness of the crime and the depth of others' reactions to it, probably with very little natural talents, then transposed to an alien southern England environment and expected to kick-start his life, make new friends and accomplish something, someone who probably already had a low self-esteem and feeling of self-worth, as if life wasn't confusing enough engaging in a sexual liaison with one of his guards, which surely cannot have helped to rebuild any trust he might have had in the penal system and its authority with which he had become familiar.
I would just say that he had been assessed and evidently deemed not a risk to children, yet if is there an ingenuous explanation for his search for hook-ups with single mothers there cannot be one for the alluring child pornography sites: is he in fact not rehabilitated at all, a clandestine paedophile for which there is no cure, and now no hope for such people to reintegrate, as we are told he is now incarcerated once again and back on suicide watch.