The Federal Emergency Management Agency says $2.5 billion in National Flood Insurance Program payments have been made in the state as of Monday.
FEMA also has approved nearly $366 million in grants to individuals and households.
FBI supervisory special agent Douglas Veivia says benefit fraud is the most common after a natural disaster in which people seek compensation for damage that happened before the storm.
Veivia says agents will look for homeowners who try to cheat the government or insurance companies. But the big priority will be corruption allegations that stem from major rebuilding projects.