I think a more pertinent question than 'Why did no one hear anything?' is 'Why didn't his parents know/care where he was for hours during the night in a storm?'
It is an awful thing to have done and no doubt his upbringing is relevant in some way. It was always going to be a male that did it. Like it is mainly males that carry knives and use them, mainly males than commit murder.
There is something about how we bring up boys and how we socialise boys, provide role models for boys, portray boys/men in the media and sport and how we educate boys that is causing this. It's all horrible at the minute.
1 month into term and the local authority school improvement service I work for is already overwhelmed by referrals from schools about boys excluded/permanently excluded/at risk of being permanently excluded. These are all about repeated violence and aggression or occasionally drugs. Teenage (and younger) boys who will not co-operate with basic requests, do as they please, are verbally horrible-insults/swearing/ appalling sexual language- cause chaos, assault other children (sometimes sexual assaults of girls), carry weapons- 99% knives, occasionally screwdriver or hammer or other tool. Teachers put up with awful behaviour for very long periods before these boys are removed. Schools try all kinds of strategies- few work long-term. Many of these boys are known to the police and in their communities for vandalism, anti-social behaviour, drinking, drugs.
That's only those who get to the point of exclusion/permanent exclusion- not including those who don't attend school, who keep it low enough level to avoid exclusion but are persistent offenders.
Then there is the laddish culture that accompanies many groups of boys. Their behaviour in groups is very different to their behaviour as individuals. So a group of nice individuals can have this 'laddish' mentality where they become swaggering, show-offs, unpleasant to girls, overtly sexual in comments to girls, can be quite intimidating even to some staff, behave like a 'pack'. Sometimes it's low-level and easily managed but it can become problematic. It is often related to sport and the way male PE departments, but other male staff too, treat boys- nicknames instead of names, relating to them in laddish ways, accepting less from them in terms of manners and contributions to other lessons, idolising the whole football culture, bigging up good players and football becoming what defines them rather than who they are as a person. They become arrogant and don't think they need to be anything but a footballer/on the team. They don't value other subjects which makes Mrs X the History teacher's job much harder. It also excludes other boys who become isolated.
Boys' behaviour is a big issue in many schools (some very challenging girls too in increasing numbers). In every single case I deal with, awful parenting is a significant and long-term issue.
Clearly this is not every boy and there are many absolutely delightful , very well-parented teenage boys (who I rarely meet in my role), but the numbers in the very worrying groups are increasing and the highest I ever remember them.