Prosecutors who viewed film taken by divers of the boat's interior say the images support testimony from the few survivors that some 800 people were aboard when the vessel capsized as rescuers approached, with hundreds trapped in the hold.
The body retrieval operation is in its third month.
Meanwhile, Italy's coast guard was searching the waters between Libya and Sicily after 107 survivors rescued from an overcrowded dinghy told authorities some 20 persons fell overboard and their smugglers wouldn't stop to pick them up.