It's very difficult to prove or disprove the claims for these psychic abilities. The psychic could have researched the location beforehand, for example, or otherwise been provided with information. If retrocognition is real, however, how might it work? It might work in the way that residual ghost phenomena works: the event is imprinted on the environment in some holographically psychic way that we do not yet understand. Everything, after all, is made up of energy, and the energy of the traumatic or oft-repeated events remain recorded in the environment in which they originally occurred. The psychic is able to "tune in" to the specific frequency of this residual energy and "see" it or experience it. Let me stress that this is just a possibility or theory for which we have no concrete proof.