set theItems to every item of someFolder doesn't find invisibles

I’m writing a little tool that removes files from a selected device. In order to provide meaningful feedback I have set it up so first the tool finds all the files that will be deleted then later presents a progress bar as each file is individually deleted.

		tell application "Finder" to set theItems to every item of sourceFolder
		--Iterate through the items in sourceFolder
			tell application "Finder"
				set countedNumber to countedNumber + 1
				set nextItem to first item of theItems
				if ((class of nextItem) is folder) then
					--The item is a folder, so add its files to the end of the array
					set theItems to theItems & every item of nextItem
					set theItemPath to nextItem as alias
					set theItemPaths to theItemPaths & theItemPath
					-- convert alias to POSIX
					set posixItemPath to (the POSIX path of theItemPath)
					-- add POSIX path to the list
					set thePOSIXItemPaths to thePOSIXItemPaths & posixItemPath
				end if
				if ((count of theItems) is 1) then
					exit repeat
					set theItems to items 2 thru (count of theItems) of theItems
				end if
			end tell
		end repeat

The code above does not find invisible items on the device, some files and folders starting with a period, can someone suggest how I can get invisible files and folders to work in the above routine?


System Events considers also invisible files or use list folder from Standard Additions.

Note: System Events may have problems with the coercion to alias of an package folder