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To his followers in the cultlike group Nxivm, Keith Raniere was known as Vanguard, or sometimes Master or Grandmaster. Though they considered him the wisest person they had ever encountered, he called himself the Eternal Student and wore a long, white sash that could be interpreted as a sign of both superiority and humility.

To disagree with him was seen as a form of heresy or, in the parlance of his followers, a “breach” that would require penance. Those who could not right their wrongs were subject to shunning.

The racketeering trial of Mr. Raniere, who co-founded Nxivm in the 1990s in a suburb outside Albany, is just a few days old. But testimony from two former followers has already offered insight into how Mr. Raniere was said to have wielded influence and controlled his many followers.

Jurors in Federal District Court in Brooklyn have heard Mr. Raniere — who has pleaded not guilty to conspiracy, forced labor, extortion and sex trafficking charges — described as a man of good intent, as a sexual predator who abused women and teenagers, and as a fantasist who saw himself at the center of a vast government conspiracy.