As authorities pick apart the life of Las Vegas shooter Stephen Paddock, they have come across one major thread of suspicious behavior: how he handled his money. In the last three years alone, more than 200 reports about Paddock’s activities, particularly large transactions at casinos, have been filed with law enforcement authorities, ABC News was told. While some of the reports centered around "suspicious activity," most were "currency transaction reports," which casinos are required to file with the Treasury Department's Financial Crimes Enforcement Network when a person withdraws or deposits more than $10,000 in cash.