Iago and his brother joined Francisco de Orellana's expedition to Akator and came away with a share of the city's treasure. However, on the journey back to their ship in 1546, Iago's throat was slit when Orellana turned on the entire group to prevent them taking the Crystal Skull in his possession.
Behind the scenes
All six of Orellana's men are shown as mummified remains in Indiana Jones and the Kingdom of the Crystal Skull, and they are named in James Rollins' novelization, but only one has his face revealed. No source specifies which of the conquistadors that man is.