Rsenis Mitin, 30, discovered soon after his 2am encounter that a gold necklet valued at 125,000 baht was no longer where it should have been, around his neck.
In going through the database of ladyboys at Kathu Police Station, Mr Mitin pointed out a couple of people and officers called them in for questioning.
The two were from a group associated with the prime suspect, a ladyboy nicknamed Dang.
Police are now keen to talk to Dang and assess whether he was in the vicinity when Mr Mitin's necklet vanished.
A crackdown by police in Pattaya, where loitering laws are currently being enforced to reduce the number of ladyboys around the ''family-friendly'' resort city in the early morning, could see some move to Phuket.