Where is the truth? My humble opinion follows:
If I may say so there are two worlds. One is outside - the physical world, the universe itself. The other is inside - our mind. I make this distinction because we have the power of imagination. This exceptional mental tool allows us to go beyond the limits of the physical world e.g. we can think of unicorns, santa claus, etc. I consider this unique ability of the mind sufficient to warrant the distinction inside and outside even though the mind is obviously part of the physical universe itself.
That said let us attempt to answer the question "Where is the truth?"
First the mind. In this particular world resides some truths that are arrived at through the sole us of or most powerful thinking tool - logic. A good example of truths that exist only in the mind is pure mathematics. In such cases we could, without erring, answer the OP's question by saying truth is in the mind.
Secondly, the physical world. This is not so easy for the simple reason that our minds cannot be factored out - we are doomed to think, so to speak. However we can still make a distinction here that should allow us to consider the truths of mind and the truths of our physical world as separate. How I make this distinction is that truths of the physical world require a correspondence between the physical world and the mind. For example...if a tree falls you should also be thinking a tree is falling. This additional requirement is absent in truths of the mind alone. Since, in this case, truth is a relation between the mind and the physical world I don't know how to describe a locus for such truths. It's at the boundary between the mind and the physical world - that's the best I can do.
Another issue here is that mind-truths like mathematics are absolute (as far as I know). They're unchanging...2+2 is always 4. Static.
However truths of the physical world are in a state of flux in the 4th dimension - time. As observers of nature we're always in the shadow of the problem of induction, as is all of science, and that may warrant the additional question ''when is the truth?''
It's all bullshit.