and no body is able to recover it by any means.
well theoritically once written on HDD it can be recovered ... but few technique what u can use which will make it so hard that vertually it would be imposible to recover...
what u can do is write many times on the same location of HDD (cluster) so the 1st data fade out so much that vertually its unrecovarable..
few software can help u.. for an instance System mechanic comes with a Inbuilt tool to delete files in that format... u can google too for individual tools... as i have never used ny such...
best would be a low lavel format of the HDD...