For some days Del Ferice's movements were narrowly watched, but with no result whatever.

Then the Cardinal sent for the police register of the district where Del Ferice lived, and in which the name, nationality, and residence of every individual in the "Rione" or quarter were carefully inscribed, as they still are.
Running his eye down the list, the Cardinal came upon the name of "Temistocle Fattorusso, of Naples, servant to Ugo dei Conti del Ferice:" an idea struck him.
"His servant is a Neapolitan," he reflected.

"He probably sends his letters by way of Naples." Accordingly Temistocle was watched instead of his master.

It was found that he frequented the society of other Neapolitans, and especially that he was in the habit of going from time to time to the Ripa Grande, the port of the Tiber, where he seemed to have numerous acquaintances among the Neapolitan boatmen who constantly came up the coast in their "martingane"-- heavy, sea-going, lateen-rigged vessels, bringing cargoes of oranges and lemons to the Roman market.

The mystery was now solved.
One day Temistocle was actually seen giving a letter into the hands of a huge fellow in a red woollen cap.