How to send an image to the back (layer) using Applescript in Keynote?

I'm inserting a new image into an existing Keynote document. When the image is inserted, it is on the front layer covering some other objects. I would like to send it to the back layer. Is there a built-in Applescript command to do that?

tell application "Keynote"
	activate
	tell (open result_keynote)
		tell third slide
			tell (make new image with properties {file:screenshot_file})
				set height to screenshot_height
				set width to screenshot_width
				set position to screenshot_position
                -- set layer position here
			end tell
		end tell
	end tell
end tell