He is 7 and has some behaviour issues and DB & SIL are supposed to be waiting for a referral to CAMHS. Apparently he was assessed by someone as having zero empathy.
At the start of the summer holidays he was caught strangling my mum's dog with his lead. (He has never been kind to animals.) My mum spoke to SIL who decided to buy him a kitten on the way home. 
Fast forward to yesterday and the kitten was found trapped in the fridge!
Fortunately it was still alive. Nephew owned up to putting him there.
My mum is distraught and convinced he's going to kill the cat. My dad's worried about my nephew's behaviour. But DB and SIL won't accept there's a problem!
I've posted on here before about some private counselling and someone suggested CAMHS, which I've mentioned above.
His punishment yesterday was to be locked in his bedroom until he admitted it was him. He was there for 4 hours!! So I feel the parents need some help too tbh.
Just looking for some advice really. Feel a bit helpless and maybe that I should be doing more.
Thanks.