The recent federal trials that ended in the quick convictions of Sheldon Silver and Dean G. Skelos laid bare a world of greed, flagrant corruption and abuse of power in Albany, with evidence showing payoffs taking a deceptively circular route from business interests to the elected officials whose help they sought.

But one man who was a key player in both cases — and identified by the government as a co-conspirator at the trial of Mr. Skelos, the former Republican majority leader of the State Senate, and his son, Adam — never appeared in the courtroom.

That man was Leonard Litwin, the 101-year-old owner of Glenwood Management, an influential developer of luxury high-rise apartment buildings in Manhattan that is among the state’s most prodigious political donors. Prosecutors named Mr. Litwin as a co-conspirator during a sidebar conference with the judge and defense lawyers that went largely unnoticed.

Image Leonard Litwin, the 101-year-old owner of Glenwood Management.

In addition to its role at the heart of the government’s case against the Skeloses, both of whom were convicted of bribery, extortion and conspiracy this month, Glenwood also figured prominently in the federal corruption trial of Sheldon Silver, the Democratic assemblyman and former speaker who was convicted of extortion, wire fraud and money laundering 11 days earlier.