I've come to AIBU for advice because I know it gets the most traffic. My SIL is raising her step son who is her ex partners child, they split up when he was 5 but his bio mother hasn't been in life since he was pretty much born so hes always called her mum and came back to live with her age 13, hes just very recently turned 16. His dad is useless, only thinks of himself and DN had been pulled in every direction after his dad cheats on another woman and moves onto the next and has more kids and so on. His dad is uninterested, he barely even texts him. SIL is very loving but works long hours and drinks heavily. I mention all this because he's had a fairly traumatic upbringing.
DN hasn't been I'm school since just turning 13, SIL wanted him in school but her ex had parental rights so he didn't bother and he's fallen through the cracks, SS have never come knocking. He was also diagnosed with autism age 13.
He's in the house 24/7 on the computer. Police came to the door almost two weeks ago about a report that he'd been sending neo nazi stuff and decapitation videos to another teen, he denied it but they have evidence. SIL has buried her head in the sand and has only just told us. We spend a lot of time together also with my sisters kids, trips away etc and the boys are all close (11 and 7) so I spoke to my sister who spoke to my 11 year old nephew (12 next week) and he said DN had shown him execution videos and porn. He also said DN is on the dark web and has a whole network of friends, hackers etc and neo nazis and argues with some of them. My 12 year old nephew was shaking like a leaf when being asked questions but he was able to give us a lot of information. I'm really troubled by it all, SIL isn't really taking it seriously, she's someone who buries her head in the sand. I'm concerned for the safety of DN and the stuff he's watching and him harming someone or someone harming him, the police said to SIL when they came out to call them if anyone came to her door but she didn't know what they meant at the time and asked them basically no questions or hasn't followed anything up.
I want to protect DN but also my other nephews and my own child who is only a toddler. I feel like it's almost falling on my shoulders because none of the adults who are meant to be responsible for DN are doing anything, his devices haven't even been checked and he's still at home all day on the computer. I mention his autism in this because he is vulnerable, his upbringing has made him look for a sense of belonging I think. He acts younger than 16. No-one is doing anything. Where would I start? Where would SIL start? He could over power her easily if she tried to take his devices.
I appreciate anyone who made it to the end!