Murders in the Zoo was made towards the end of the first, post sound horror boom and just before the rigorous enforcement of The Motion Picture Production Code came into effect in 1934. The latter point is relevant because despite its age and being very much a product of its time, this movie has a grisly streak running through it. Had it entered production a year later I suspect it would have been a lot tamer both visually and thematically. Murders in the Zoo begins and ends with scenes that certainly leave an impact and stay with the viewer. Most casual movie viewers probably consider pre-war cinema to be theatrical in its acting style and somewhat tame, but that is not the case with Murders in the Zoo and many other movies from this time. Until tighter regulation was introduced, there was a brief period between 1928 and 1934 when movies were as violent and lurid (in principle) as contemporary cinema. All the things that are deplored today in certain quarters, where equally decried then.