Sinfully Rich by Hulbert Footner — Read

The Ware apartment had now been combed from top to bottom by two of the most expert searchers in the business. The jewels had not been found, and this appeared to exonerate the servants. All persons who had made deliveries at the service door were being checked (in case the loot had been handed out) and the guests quietly investigated. Carpenter, the detective employed by the insurance companies, did not really expect to find the thief until an attempt was made to sell the jewels. He frankly declared himself at a loss in this case, because it was apparently the work of an amateur thief, and you could never tell which way an amateur would jump.

Radigan and Mike now divided their forces for the time being. The former went back to Headquarters, where he had a lot of routine work to start going. He had to try to establish through police channels what sales of hypodermic syringes had been made within the past few days. The hospitals and so on were to be circularized to discover if the theft of such an article had been reported. The pathologist had told Radigan that one of the bigger syringes had been used, one with a capacity of 22 cc. or more. This narrowed the field. Radigan was also to order the sewer catch-basins in the neighborhood to be cleaned out, and the contents examined.