Three of the old ladies are, in fact, well into their 70's. However Ellen Corby, famous as Grandma Walton on The Waltons, was only 46 years old when this episode aired.
The elderly ladies live at 909 Lexington Avenue.
O'Finn is 45 years old and a detective first-class with over 20 years in Homicide.
The actress playing the corpse of Miss Elizabeth is uncredited.