One of the ways in which citizens can be of great help is their awareness within their set of skills, life situations, and activities.

For example, an agricultural supply outlet people have an idea of what are the normal types of customers who might purchase ammonium nitrate fertiliser. They are in a good position to sense if a customer is “off”, doesn’t seem to be a farmer, etc. (Real life example: Following the OKC bombing a news crew from a major city went to an ag supplier in an adjacent state to get some ammonium nitrate to show how easy it is obtain. The clerks noticed the out-of-state plates, their clothing was too delicate for farming, the customers were not familar with farming terminology, etc. They called it in to the auhorities. Spoiled the news story but provide a good illustration how citizens can discern suspicious *behaviours* from their areas of expertise.