Ahma:
I agree that we should probably gently divert this one in the direction of MCAT to handle. The only "Actual" crime we know of that she committed is the hospital murder, which they are already investigating, and our "evidence" that it is her is the sort that is most definitely not (yet?) submissible in court. Also, we've got to come up with a descent cover story for how we know she's a student at Juuban High without giving away our own secret identity for the time being. That second one might be tricky.
Mamoru:
I'm for either getting him his own body or reuniting his portion of their soul with Endymion in some manner. It probably depends on what we can figure out about the exact metaphysical relationship between the two, and if they are still indeed two parts of the same soul or if the accident somehow sheared off Mamoru from Endymion. My money is on the former, or at the very least them still having some sort of tether between one another, given that Mamoru did have some ideas of who Endymion is despite the two never having crossed paths (that we know of) since their discoproration.
Speculatively, in the event of reuniting them, it may be entirely possible that Mamoru will gain and grow from Endymion's knowledge and experience in the modern era through becoming a whole being again, rather than having to "grow up" the long way. We really won't know until we start exploring the possibilities.