He has my bank account info, and I just want to know where I stand legally.
Legally you can't keep the money. It would either go back to the originator or to Government unclaimed department.
I got a bunch of missed calls from an unknown number and a really unprofessional email from a guy who supposedly worked for UNICEF saying I had 4 hours until I am suppose to be visited by police and that there was nowhere I could run to.
These are common tactics employed to ensure you take some action and transfer the real money somewhere. Do not succumb to such tactics.
The money is still in my account I have not touched it.
Advise your Bank immediately that there is this deposit into your account that is not your's. Let the bank take appropriate action.
Do not authorize Bank to debit your account. The max you can do is authorize the bank to reverse this transaction. The best is stick to statement that said transaction is not yours and Bank is free to do what is right.
There is a small difference and very important. If you authorize bank to debit, you have initiated a payment. So if the original payment were revered by originator bank, you are left short of money. However if your instructions are very clear, that this specific transaction can be reversed, you cannot be additionally debited if this transaction is reversed.
He has my bank account info,
Depending on how easy / difficult, my suggestion would be monitor this account closely, best is if you can close it out and open a new one.