Book of Jubilees

The Book of Jubilees is an apocryphal scripture which narrates the genesis of angels on the first day of Creation and the story of how a group of fallen angels known as the grigori[?] mated with mortal females, giving rise to a race of giants known as the Nephilim. The Nephilim which were in existence during the time of Noah were wiped out by the great flood. However, biblical accounts found in Numbers, Deuteronomy, and Joshua indicate that the Nephilim, as well as other races of giants who were the progeny of the Nephilim, were reconstituted after the flood, presumably by angels who fell from grace after the flood.