DR. KANTRIPP, the Lampreys’ doctor
SIR MATTHEW CAIRNSTOCK, a brain specialist
DR. CURTIS, police surgeon
DETECTIVE-INSPECTOR FOX of the Central Branch, Criminal Investigation Department
CHIEF DETECTIVE-INSPECTOR ALLEYN of the Central Branch, Criminal Investigation Department
DETECTIVE-SERGEANT BAILEY, a finger-print expert
DETECTIVE-SERGEANT THOMPSON, a photographic expert
POLICE-CONSTABLE MARTIN
POLICE-CONSTABLE GIBSON A police-constable who has read “Macbeth”
DETECTIVE-SERGEANT CAMPBELL, on duty at 24 Brummell Street