Don't know about the specifics of this case, but finding a wing or two some distance from the fuselage is a text-book sign of an in-flight breakup. Wings and tailplanes tend to flutter almost straight down after they come off, while the rest of the airframe carries on for a bit. 500 metres apart is possible if the breakup occured at an altitude several times that: say 2 kilometres, or about 6,500 feet AGL.
A quick Google finds that Dennis Burke has posted the accident reports on-line. Have you seen these:
http://www.skynet.ie/~dan/temp/C-47%2043-16394.pdf
Page three states "left wing hit the trees and was torn off ... the lift of the right wing caused the aircraft to cartwheel". That could put some distance between one wing and the rest of the aircraft.
also see
http://www.skynet.ie/~dan/temp/Crew%2043-16394.pdf