The burglaries happened at the Islamic Cultural Center on the Upper East Side of Manhattan.
According to police, the burglar entered the mosque on June 8 with members who were arriving for morning prayer. The thief hid in a closet until worshipers had left, then took money from the donation boxes.
The second burglary took place on Thursday. Police said the burglar broke in by shattering a glass door to the mosque and again removed money from the donation boxes.
Police believe the same person committed both burglaries.