I need advice

Ok I need some advice. I own and live on 15 acres. The property next to me no one lives on but the owner gives permission to 2 people to hunt it. One guy hunts by himself, the other brings family and friends. Total acreage is 30. The guy who hunts on my side is the one who brings others out occasionally. This year he hit a buck bow season, I helped him track it, we didn't find it. A week or so later he shoots 2 bucks the same night, finds neither. Shoots a fourth buck, a 6pt, turns out to be one he wounded the week before. Yesterday I'm out with my 6 year old trying to get him his first deer, a shot rings out close by, it's him saying he shot a wounded deer ( I texted him). 15 minutes later a 6 pt comes by, as it gets closer I see it's wounded, my 6 year old was getting it lined up when it falls. It was liver shot, the deer he claimed was wounded but only had 1 hole in it. So, he shot 2 6 pts, ( both 3x3 ). His daughter shot one in youth season (truly am happy for any youth to get one), but that's 5 bucks shot from a relatively small parcel and illegal cause one didn't have more than 4 points on one side. He's out hunting again today, with his adult son. I drug the deer out for him yesterday, never saw him tag it. I'm worried about causing issues and make the situation work. I've been a good neighbor, even picking up car replacement parts for him when his vehicle broke down. In my opinion he's been very unethical but not it's actually breaking the law. Any advice or opinions? It's frustrating cause I let smaller ones go only to have someone there shoot them ( I know that's hunting ) but the biggest thing is my son, he is so upset and trusted by the whole thing. I keep telling him if does things the right way he'll be rewarded but it's tough when he sees someone not doing it right get rewarded.

I need advice