My wife and I are the parents of six children; the older three ours and the younger three are an adopted sibling group; they have been part of our family for about four years. The oldest adopted son has been a real challenge to raise, and to cut to the point, left home when he turned 18 and found/moved in with his biological family. This has happened in the past six weeks.

In the process of leaving, I took him into our insurance agent and he set up an insurance account in his own name for the car that I bought for him with his money (when he was 17). After the insurance was set up, I signed off on the title to the car, putting it in his name. He no longer attends his old high school, but I heard through rumors that he (at least attempted) to have himself transferred to the high school in his home town. I have basically heard nothing more from him.

I am trying to figure out the emancipation laws in Indiana, but can't seem to wrap my brain around them. As far as I understand them, the boy turned 18 and voluntarily left home, which emancipated him. Am I, as his adoptive father, responsible for his subsequent actions (legal, monetary, etc.)?

First as an adoptive parent you will always have some moral obligation but that is another story.

Once he turns 18 you are no longer legally responsible for any newly young adult. ( at 18 they are no longer a child).

There is nothing to do or file what so ever. If you have co-signed for his insurance you may contact them to have your name removed from all paperwork, if you name is on any joint bank account or credit card, that needs to be addressed.

You will want to be sure he registered the car into his name, if you merely signed it over and he did not take it to the state office and change ownership, then you may still be held liable unless you have a receipt or proff that you signed it over. I had a old car that I sold someone, 4 years latter I got a towing and impoundment bill on it. They never changed the registiion on it. It went on my credit report and more , took me over a year to straighten it out and I had proof that I sold it.