Most of what is publically known about the Roby Murders is only that which was reported in the papers, or then circulated as hearsay. During the campaign, the investigators were able to confirm (in part via a letter from Doctor Lionel Trollope) the following about these grizzly murders:

• On October 14th 1926, Herbert Roby and his adult daughter Georgina were murdered at their home in Curzon St, Mayfair.
• Mr Roby, a retired diplomat, was killed by a deep wound to the upper chest and completely exsanguinated, though almost no trace of his blood was found at the scene.
• Georgina was killed by 2 or 3 blows from a large sharp implement, such as an axe, and bled profusely.
• Mr Roby's younger son, Alexander, was arrested at the scene after claiming responsibility, but instead of being charged was committed to St Agnes Asylum, Herefordshire.

Eventually Dr. Bartlett was able to conclude that Roby had attempted to summon creatures such as The Springer Mound Monsters to kill his Father and that this creature or creatures got free of his control. While Bartlett, had no real evidence for this outlandish speculation, he knew them to be the only answer that made any sense.

After meeting Roby in Carcosa, the party learnt that the deaths of his Father and sister Georgina were a terrible, painful mistake, one that should have never happened, and which Alexander regretted to the end.