If you search "Megiddo Guy OiC 9" you will find a .pdf of Guy's excavation at Megiddo, and on page 49 is an article with pictures on Haman's scaraboid found at the site. The scarab depicts a griffin wearing the double crown of Egypt standing over a locust. Griffins are prominent in Persian poetry and art.
'Ahasuerus' was a ruling title like 'pharaoh'. The king of Persia was Darius I Hystapses in the book of Esther. Cambyses II, before him, had conquered Egypt in 525 BC. Darius I Hystapses may have made Haman an overseer of Egypt and Canaan, with Megiddo as an administrative center for western lands.