यं चात्र गूढाजीविनं शङ्केत तं सत्त्रिणापसर्पयेत् ॥ कZ_०४.४.०५ ॥
yaṃ cātra gūḍhājīvinaṃ śaṅketa taṃ sattriṇāpasarpayet ॥
Whomever one suspects here of living by a concealed livelihood (i.e., covert criminality), one should have him approached/handled through a sattrin (an operative placed as a trust-building intermediary).
A covert operative who gains trust by appearing as a benign helper (often linked to a charitable feeding house/hostel), used to initiate controlled interactions with suspects.