Most of what is known about the Roby Murders is just that reported in the papers, or is hearsay (and the statement of Doctor Lionel Trollope). Over the campaign the investigators were about to confirm the following:
Dr. Bartlett has concluded that Roby attempted to summon creatures such as The Springer Mound Monsters in order to kill his father and that the creature or creatures got out of hand. He has no real evidence for this outlandish speculation.
After meeting Roby in Carcosa, they learnt that the deaths of his Father and sister Georgina were a terrible, painful, mistake, one that Alexander will regret to the end of his days.