3Do a photo check. Save a copy of their profile picture. Use Google image search. Check the results. Are they already marked up as scammers or is the return illegitimate in some way? Report to the dating site giving the evidence, including any website links.
4Check other photos you receive. Look for signs that don't seem to gel with who you understand this person to be. For example, check the background, landscapes and even clocks or calendars. Can you see identifying features that do not match with the picture this person has built up of themselves?