What papers...specifically? I've seen report that privileged communications (as in attorney-client) may have been caught up in the confiscation. If those aren't returned, the risk of having everything getting ruled inadmissible exist. Are you saying he doesn't have the right to have that privilege respected?
Keep in mind...I'm not saying privileged communications were taken, but if it was that needs to be addressed very quickly.
As far as selling information...I have heard speculation from liberals, but have heard/seen nothing even remotely resembling admissible evidence that happened in the almost two years. If he wanted to sell...that probably would have already happened.