I am curious on the personal financial gain. I thought the deed was for $10. Anyhow, it seems there was some family tension around assets based on this.
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When a person dies, if they have a will, their will controls what happens to their assets. You can say anything you want in your will. I can give my entire estate to my dog as long as I am clear and my will is properly executed.
If a person dies without a will, their assets will be distributed in probate according to the laws of intestate succession in their state. Generally, if the decedent has a spouse, everything goes to the spouse. If the decedent has no spouse but children, everything goes equally to the children. If the decedent has no spouse and no children, everything goes to the parents. If the decedent has no spouse, no children, and his parents are deceased, his assets would be distributed equally between his siblings. There are specific rules about if one sibling is deceased but leaves children (nieces and nephews of the decedent) and it can get complicated.
So if one brother dies without a will (with no spouse and no children), and his mother is still alive, his estate would transfer to his mother on his death. His siblings would get nothing. Transferring property to yourself when you are POA for a dying person when that property would otherwise properly go to the dying person's heir (mother, for example), can be considered a fraudulent transfer.
ETA: the first $11.8 million in an estate transfers tax free in 2020 so if your estate is estimated to be under that number, there are no estate taxes when your property passes to your heirs.