Mr Cronin said he was a tourist staying in the Nana red-light area on Sukhumvit Road and had spent all his money in only a month. He then decided to rob the bank.
The suspect wanted to use the money to buy a plane ticket back to Australia.
Mr Cronin travelled from Nana to Saphan Kwai by BTS Skytrain and spent five minutesscouting areas outside the Thanachart Bank before the robbery, he added.
Police escorted him to Thanachart bank Morchit branch late today for a re-enactment of his bank robbery.