After you have already gone into the museum and been arrested and carted away. (True.)
you have to catch a thief on counterfeit island and when you catch the thief you will get a medallion
In Counterfeit island, you chase him.
Click PRINT.
Night
The art thief is back on Counterfeit Island. As part of Counterfeit island, you don't need to do anything in Early Poptropica except get the key from the curator at the Pop Art Museum, then return to Counterfeit Island to open the Inspector's house.
night right after you get caught the thief is the investigator
Once you get the time card from the security guard (he's at the Clown Store) you can check the surveillance video for the likely time, and get a photo of the thief.
the mimes do he's at the music place
nothing you just wait and then the thief will come and you will jump on him and get arrested
He is in the clown store.
hang from the light above it
Go back the museum : you have a package waiting for you.