TRANSFORMATION by ROBERT BARR

Two brothers, owners of a clock and watch shop in Paris, experience a visit from a very suspicious man whom they suspect is a thief determinded to rob them. They report him to the police, who end up questioning him, and bad things result.

Here is that promised link to two of our Robert Barr stories:  

https://www.podchaser.com/podcasts/1001-classic-short-stories-tal-46960/episodes/an-alpine-divorce-and-the-rigo-82867169