When an investigation involves possible work activity, secondary employment, self-employment, contracting, or business involvement, focusing only on a residence can narrow the field too early.
Develop the work ecosystem
Public business records, licensing information, permits, professional profiles, public social content, job-site references, equipment, vehicles, associates, and recurring locations may help identify where relevant activity is more likely to occur.
Use the information to improve the question
The objective is not to label an indicator as proof. It is to develop a more precise investigative hypothesis: Is there current work activity? Where does it occur? When is it most likely? What independent source could corroborate it?
Then decide whether field work adds value
Once likely locations and timing are better developed, surveillance or other field activity can be more focused. In some cases, records or interviews may answer the question without field work at all.