I suspect that it will be dismissed as a suicide, although there are many unanswered questions.

1) Why didn't the twin report the brother missing?
2) Why was the twin's behavior so strange?
3) Why did he make up these outlandish stories?
4) The boy was found hung, but not hanging
5) Why did he say he had searched that area, and yet a woman walking her dog stumbled upon it accidentally?

I'm sure that we'll never get all of the answers. The twin's behavior can be... explained if he knew what his brother was contemplating but did nothing about it.

If you Google "County with most unsolved murders" you will not come up with a county that includes LA or Chicago, the top answer is our rural county.