Miss Marple is Nemesis, the ancient Greek goddess of Retribution.This is joked about in the beginning of the story Nemesis, but what if it were the case? It would explain how she was always around when murders happen and how she has the powers to solve them. And yes, there should be a Wonder Woman crossover.
Miss Marple is a sort of Psychopomp who guides those facing death and tragedy.She shows up at murders and helps everything work out. Maybe she's an angel of mercy and leads those who remain to resolution. Maybe she's an angel of death and drives people to murder because of her presence. Maybe she's some kind of demon or deity who just does it because it's fun. But come on, how do all of these murders manage to involve her all of the time? It has to be something!
Miss Marple is not an expy of Caroline Sheppard from The Murder of Roger Ackroyd—she is Caroline Sheppard.The reason that Poirot allowed the killer to commit suicide rather than being arrested in Murder of Roger Ackroyd was out of respect for Caroline and fear that she would be disgraced by the revelation of the truth. So it seems highly likely that if the manuscript of that case were published, the names of all people and places would have to be changed first. According to this theory, "King's Abbot" was actually St. Mary Mead, and "Caroline Sheppard" was actually Miss Marple, with just enough details about her changed so that her neighbors wouldn't recognize her if they read the account of the crime.
Raymond West, whom Miss Marple calls her nephew, is really her son.It's only fair that Miss Marple should have a secret of her own.