Well , I don't either but it is possible.
The easy way to find out the truth is to find the drive or to have him under the polygraph.
The polygraph doesn't work -
http://rationalwiki.org/wiki/Polygraph. How hard would it be to find the unspent coins on the blockchain?
Not hard , we have the time frame and you just have to go through the blocks in that period. But most of them haven't move so they could be his or Satoshis ones.