On the Trail of SAC Capital's Steven Cohen .

By Bloomberg/ Reuters

One day in 2008, David Munno decided to vent to his boss. Munno, a health-care analyst then employed at SAC Capital Advisors, was mystified as to why the hedge fund was building up large positions in drug companiesElan (ELN) and Wyeth. The positions were unhedged, which made the trades even riskier. And there was no obvious strategic explanation, other than that a relatively untested 34-year-old portfolio manager named Mathew Martoma had been pushing heavily for the trades.

Martoma was viewed skeptically by many of his colleagues, according to a current SAC employee who was not authorized to speak for attribution. But the one person who trusted him was the only person who mattered: SAC founder Steven A. Coh