Tico Times recently published a series of articles to commemorate the 30th anniversary of the La Penca bombing. The articles are written by several journalists, some of whom were actually present when the bomb exploded during a press conference given by Eden Pastora, a former Sandinista who became disenchanted and left Nicaragua to head up the southern front of the contra.
They seemed to have figured out who actually planted the bomb, but there doesn’t seem to be conclusive evidence as to who ordered the bombing- if it was the CIA or the Sandinistas.
Here is a link to the articles: