How were the details of the iran-contra affair discovered?

The Iran-Contra affair was discovered when a senior officer of the Mehdi Hashemi revealed the deal that was made.  On November 3, 1986, a Lebanese magazine Ash-Shiraa published an article about the weapons agreement.  The delivery of the weapons was discovered after a plane carrying the weapons was shot down and a survivor named Eugene Hasenfus was taken custody by Nicaraguan forces. In a press conference held in Nicaragua, Eugene disclosed that two of his colleagues  Max Gomez and Ramon Medina were part of the Central Intelligence Agency. The article published by Ash-Shiraa was confirmed by the Iranian Government.