He was already under suspicion, and by making the matter public I secured the services of about ten amateur detectives, who would be watching him unceasingly, and being himself aware of their watchfulness he would not dare seek further to destroy the document. 
I did not hire any detectives for him.
mnli hypothesis: I did not hire any detectives for him. premise: He was already under suspicion, and by making the matter public I secured the services of about ten amateur detectives, who would be watching him unceasingly, and being himself aware of their watchfulness he would not dare seek further to destroy the document. 