Checking for existing file & supported file types

I’ve found plenty of code showing how to check for existing files to load into a flash scene but the only thing they check for is whether or not the file begins to load. The problem I’m having is that the file I’m checking for exists but is a .tga which apparently is not supported in AS3. I really only need to check to see if the file exists and if so skip to the next file check. If it doesn’t exist I want to add the file name to a log…

I’m wondering if there is some sort of “myFile.exists()” method or something. I’m also wondering if checking based on the IOErrorEvent would work. The two errors I get are: “URL Not Found” (if I change the file extension to a known .jpg) and “Loaded file is an unknown type.”