The Crystal Beads Murder (1930), by Annie Haynes and ???

Clue in the crystal....Can Inspector Stoddart read the signs?

Annie Haynes had not completed the manuscript of The Crystal Beads Murder before she passed away in 1929 from heart failure, at the age of 63. (She had suffered from rheumatoid arthritis for fifteen years.)  A sister mystery writer offered to complete her friend's manuscript, a proposal to which Haynes' publisher, The Bodley Head, eager to have one last Annie Haynes detective novel to place before the voracious mystery reading public in 1930, assented.

I have an idea who this woman mystery writer may have been and I will throw out some clues in the coming days.  It's a matter I discuss in my introduction to the forthcoming reprint of The Crystal Beads Murder, by Dean Street Press. Care to make any guesses?

The Crystal Beads Murder concerns the slaying of a libidinous swine in a summer-house on the grounds Holford Hall, the Midlands country estate of Lord and Lady Medchester.  Suspects in the slaying naturally are numerous, presenting another challenging case for Inspector William Stoddart, who previously solved murders in The Man with the Dark Beard, The Crime at Tattenham Corner and Who Killed Charmian Karslake?  In the current case he does have one clue: a broken section of a crystal bead necklace that his assistant, Alfred Harbord, found in the dead man's overcoat pocket. Where will the clue of the crystals beads take the investigation?

The Crystal Beads Murder is written in Annie Haynes' best vein, with intriguing plots complications and interesting characters alike capturing the reader's fancy. It will be out in the fall, along with the other Stoddart mysteries; and Annie Haynes' eight other detective novels will soon follow.