Neighbours child causing stress injuries

[Spikeyplants]

In-laws neighbours have an autistic child aged about 8. He is left in the garden on his own and will climb up the fence to stare look over. They've have rubble left in the garden from renovations. He has thrown plates, glasses, large rocks and parts of bricks which shatter on my in-laws patio and damage pots. They've tried speaking to the parents, it stops for a day, then re-starts. Last week, an elderly visitor was hit by part of a brick causing her to bleed.
The parents are no longer answering the door and refusing to engage. Should they keep a diary and notify the council, the police or someone else?

Social services and the police!

They are not supervising their child. Sounds like they need more support with them so I would contact social services.

Yes, whilst there is nothing wrong pm the face of things in a child being in the garden the lazy prices either need to supervise their child or remove all projectiles from their garden given their child lacks the impulse control to prevent them causing harm to others and damage to property. I'd be tempted to lob a brick back at their window to be honest.

Police.

If he's injuring people they will have something to say about it.

Agree.

I'd also look to stick a high trellis on the fence between the two gardens to physically stop him throwing items over.

They did ask the neighbour to install a taller fence or netting on their side to prevent the daily damage- but that hasn't happened. I don't feel my in-laws should be paying out themselves to protect their property and friends.