I wouldn't say that it was no longer needed, or no longer used. RFG did use it at conferences.
Had RFG claimed it was stolen, he would have had to file a police report. That would be chancy. If he said, **I accidentally dropped it in the river,** and it turns up, it would be impossible to prove that it wasn't an accident. Only if the police would get a warrant to search him home computer or someone saw him toss it into the river would there be any question. However the point that any damage to the drive would be suspicious is well taken.
My problem with any Sandusky connection is twofold.
First, the 1998 police report was sent via fax, indicating that there was a hard copy at the DA's office. If RFG was working on the case, why wouldn't the hard copy remain on file, along with any information. He would have had to scan that into a digital medium, then destroy the hard copy (copies). He would then have had to make sure that there was no digital copy in the office.
Second, why on earth do what would have been secret searches on Sandusky. For anyone to have found out what RFG had, they would have had to check his browser history. Unless he is basically under criminal investigation, nobody will check. It is the same with any hard copy. RFG would be trying to keep it secret that he was looking at Sandusky from LE, potentially.
It is the same problem with any Sandusky information on his computer. The only people he would be hiding it from are LE and possibly staff (quasi-LE).