17
Oct
Sources close to the situation tell TMZ ... Liam Payne and his girlfriend Kate Cassidyarrived in Argentina on September 30, posting several social media posts together showing them having fun on vacation. We're told she left Argentina on the 14th. Liam stayed behind, and checked into the CasaSur Palermo Hotel. We're told someone at the hotel called 911 to report an "aggressive" male at the hotel today ... which lines up with what witnesses told us about Liam's behavior in the lobby. Liam Payne is dead after a fall from his hotel balcony in Argentina ... TMZ has learned. The former One Direction singer…