The script held in the Crawford Collection in the AFI Research Collection contains the following character notes (excluding regular characters):
'GRAHAM ELLIS Late twenties, early thirties, Ellis is mentally disturbed with a fetish about cleanliness. He is intense, precise, methodical and shows little emotion. Lead role.
'MRS. FOSTER Ellis's landlady. Age not important. A bossy, nosey woman.
'MR. ELLIS Graham's father. An elderly man, retired, quiet, unassuming.
'MRS. ELLIS Graham's mother, also elderly. Quiet, devoted to her son, motherly.
'JILL PATTERSON Patterson's wife.
'DR. TED WRIGHT. Psychiatrist. Middle aged, self assured.
'JIMMY PATTERSON Patterson's son, aged 10.
'LUKE PATTERSON Patterson's son, aged 8.
'SALLY PATTERSON Patterson's daughter, aged 5.
'MRS. CAHILL Middle-aged. Mother of woman killed at Zoo.
'JOHN PIPER Young man at Zoo. His girlfriend is shot.
'JUDY ARCHER Piper's girlfriend.
'MRS. FELTON Mrs. Cahill's daughter.
'MR. MCBRIDE Old man shot at Zoo.
'MR. FOSTER Landlady's husband.
'MRS. O'BRIEN Elis's [sic] second landlady. Middle aged.
'TWO AMBULANCE MEN ACTUAL.
'EXTRAS 3 People shot in street and onlookers.
'POLICE CONSTABLE.
'COOK IN HAMBURGER SHOP.
'MR. ROGERS. Tram Conductor.'