Mother of child arrested in Colorado while on the run from TN for murder how can we get child back to TN?

You need to begin with a lawyer in CO. Because the child is(it seems) in CO because of child neglect/abuse that happened in CO, a separate jurisdictional ground exists for CO to have jurisdiction over the child. Father should “win” against a third party, but may have to appear in CO. It may be, unfortunately, that you need an attorney in each state, at least until the child is back here. A TN attorney can likely get you a custody order, but then you still have to take that order to a CO court, so it may be more efficient to start with that CO court.