Though if fraud or hoax can be discarded, it's hard to dismiss the implications of Bob Snow's experience for the reliability of regression in at least some cases:
What he proves, to my mind, is that human beings have an at least latent ability to access information that they can't possibly have known through "ordinary" means -- and that's about all one can say. It doesn't prove that past life regression actually regresses one to past lives; it doesn't prove that some coincidences aren't coincidences; and it doesn't prove that spirits are involved. All of this kind of thing depends on narratives that human beings create to provide an explanatory framework.
Marisa is also credible insofar as verifying that she has access to information most of us don't have access to -- she has a similar kind of down-to-earth attitude to life in general as the detective. Alex asks whether I trust what she says; well, yes, I do tend to, but not necessarily her interpretation of its source. For me, that's her narrative, and it's influenced by her personal experiences and opinions, which are in turn influenced by the culture she was brought up in, no less than the shamans she mentioned. It might be a wee bit harder for her to see that she herself is subject to similar influences from her own culture.
Of course, Marisa's interpretation could be correct. There really could be spirits, likewise past lives, reincarnation and ETs whom we might ourselves at some stage have incarnated as. But, like Robert Snow the detective, I'm agnostic about what interpretation to place on it all. Somehow everything that has ever happened in the universe may not to be forgotten; somehow some people may have some degree or other of access to it.
The universe may have or be a mind that retains every memory, and we (as alters?) may have the potential to access those; it may also have thoughts about non-eventuated possibilities that we might also be able to access. Our personal/cultural narratives may influence how we perceive this information; we may perceive spirits and ETs, but maybe those are just interpretations that seem to some of us to be real; maybe our belief in them is sufficient to lend them a kind of concrete reality.
However, just as science creates models of reality which scientists often come to think of as correct and not open to question, maybe we create models that it's very hard to put aside when interpreting information. These models have a kind of compelling logic to them. Scientists perceive an apparently external world, and so for many of them there is an external world composed of objects that literally are what they appear to be; and that may produce predictive results that can be used in the development of new technology. To that extent scientific models can be very useful even if not actually correct: but the extent to which they are unquestioningly believed correct contributes to science becoming more like scientism.
Paralleling scientism may be its counterpart, let's call it "psychism" for want of a better word: an explanatory framework in which we hypothesise the existence of spirits, ETs, etc. which does in fact seem to provide some kind of logical rationale for all the spooky stuff. I'm not suggesting that the "spooky stuff" doesn't exist, only that our current models of it aren't necessarily accurate. In a way, psychism depends on materialism, just as scientism does. One has to believe that what we see out there and interpret as planets really are planets in real 3D space, and that upon them (as well as on our own planet) there are real beings that live and die and possess souls or spirits.
We have to believe in the whole tacitly accepted model of reality with its time, space and matter, as much as a realm of spirit. At best, that's a dualistic view, but I lean towards a monistic view in which there is only the one kind of stuff, and since I think that's mental rather than physical, I'm an Idealist rather than a materialistic monist. Matter, space and time are useful concepts - perhaps vital for survival - but not ultimately real. However, our ideas about the spiritual are so bound up with these material concepts that we're all (even if unconsciously), a little bit dualistic. To put it another way, we're all a little bit into psychism.