The Malinsay Massacre

Crime Dossier 3 of a 4 book set that was an early progenitor of the modern mystery suspect / cold case tabletop games. The Earl of Malinsay is dead, and ruin comes to an ancient family. Did the valet really murder his master, or did the mysterious foreigner send poisoned sweets to Viscount Raeburn? Whose handwriting is on the label and who put arsenic in the peppermints? Is the beautiful Countess conspiring with her lover or is the secret of the Malinsays hidden in the past?