Mr. Duarte's political decline began when the rebels kidnapped his daughter in late 1985.
Cabindan rebels kidnapped and ransomed off foreign oil workers throughout the 1990s to in turn finance further attacks against the national government.
Last week, the leftist rebels killed one Salvadoran mayor and kidnapped two.
The rebels also kidnap a nurse and steal medical supplies.
In other violence in recent weeks, the rebels have killed one mayor, kidnapped at least four others and blown up two mayor's offices.
The rebels kidnap Miles and force reverse-brainwashing, whereupon he remembers his past and joins their efforts.
Armed rebels have kidnapped several foreign civilians and threatened to execute them.
The release is important because experts estimate that the rebels have kidnapped more than 200 Serbs, with most believed to have been killed.
In September, the rebels kidnapped three drivers and executed one to put pressure on the company.