I live in the country.
Someone dumped an adult pit bull on my road about a half mile from my house.
No tags or collar.
He/she just showed up and no one in the area owns one.

My concern is the young man who is keeping the dog.
He has asked neighbors if they know the dog.
I'm worried he's going to keep it.
This kid has been nothing but trouble- drag racing on the road, motorcycle riding in a nature preserve, driving drunk.
I'm worried he's just going to let the dog loose.

I've already stopped walking by his house with Bodhi.
Ideas?

Talk to the kid and try to convince him that it's not a good idea to keep a pit bull if he doesn't have experience with that kind of breed? And if you want to go an extra step, offer to help him find a good responsible kennel or someone to rehome the dog safely?

If your county has an animal control officer they can go in and take it from him and hold it. Then they can find a spot in a shelter for it so that it can be properly evaluated and rehomed. If there are any kind of county policy or subdivision rules you can dig up you maybe able to force him to turn it over. many counties as well as cities have permits that must be issued on pitts. If several of your neighbors report concern for the dog to the county they should do something. The big thing is doing it in a manor that doesn't make the animal control officer immediately jump to euthanizing the dog. It could be a perfectly nice dog, just not in the hands of a responsible handler. Don't want to condemn the dog for who just happened to pick it up.