Parents, teachers, family members and others who think they know the criminal well encounter a tactic that he deploys frequently -- a lapsing into silence, momentary or prolonged. Silence is a tactic by which he hides from others, by which he refuses to be accountable. In a more general sense, he utilizes it so that others have difficulty knowing him. Given that he perpetually seeks to gain an advantage over others often in nefarious ways, it is understandable that he wishes to conceal his intentions. If he is in the process of being questioned by someone who has apprehended him and discovered what he is up to, silence is a means for avoiding self-incrimination.
On a frequent basis, parents, spouses, friends, teachers, and counselors enounter this individual sitting before them, arms folded, eyes lowered or staring blankly ahead lapsing into stony silence. But there is a very busy mind scheming and calculationg. When a criminal remains silent, others are largely rendered impotent in their efforts to acquire information. Silence is an act of defiance but not in an obviously aggressive manner.
Some criminals are perceived as "the silent type" even thought to be shy and socially reticent. However, if one were to observe them in their preferred environment, they would likely see them behave very differently. The man who seems quiet and reserved may be boisterous and the life of the party under different circumstances...
One should understand then that silence serves a number of different functions for a criminal who conceals his intentions, tries to load things in his favor, then does his utmost to remain inscrutable to others.