I don't have the faintest idea where he has gone.
I don't know where he has gone
Nobody knows where he has gone
I don't know where he went.
I don't know where he went.
I don't know where he went.
There is no way of knowing where he's gone.
There is no saying how far his folly may go
Nobody knows where he has gone.
I don't even know where my older brother went.
I have no idea where he has gone.
Nobody knows where he has escaped to.
I don't know where he is.
Nobody knows where he has escaped to.