There are too many clues in this room

What is the origin of ‘There are too many clues in this room’?

Gordon Lightfoot used the line in one of his songs. It was used in Agatha Christie’s Murder On The Orient Express (the 1974 film), which was written in the 1930s. In the film Poirot recites the line to a little tune. Is it from a song?

Bumping because Murder On The Orient Express is playing on TCM right now.

Also: Might be better suited to Café Society.

Agreed.