The High Fence

First published as The Man Who Knew in The Thriller (June 16, 1934), then as The Saint and Mr. Teal in 2 issues of Popular Detective (US & Can - april 1935) and Triple Detective (Winter 1951). The titled story in the Popular Detective and Triple Detective is not the same as the book. Published in the collections The Saint Goes On and The First Saint Omnibus with the current known title.
Simon Templar, joined by Patricia Holm, goes after a man called the High Fence who tends to kill people who might rat him out. He was "England's most feared handler of stolen jewels, whose identity is so well hidden even his own men never meet him".