Could be from the ice maker. Is your ice maker working? Is the refrigerator keeping things good and cold?
About the only other place it could have come from would be from the frost build up on the evaporator. When the refrigerator goes into defrost the frost melts off the evaporator and runs down the drain hole in the bottom of the freezer. If the drain hole gets plugged the water then runs out the door.
You should be able to pull the bottom freezer basket out and look between the holes in the back panel to see if the drain hole is clear.
From what you have described it sounds like you may have already traced the leak up the wall and to the ice maker.