2020 US election - The fat lady is warming up in the wings

[Bob Schroeck]

And the answer is a qualified yes. The following comes from The Washington Post (here; if you've used up your free reads at the Post this month, Google Cache is your friend):

A person may refuse to testify, even when subpoenaed, on the grounds that the testimony may expose him to criminal liability. But if the prospect of criminal liability disappears — whether because he has been granted adequate immunity by prosecutors, or because he has accepted a presidential pardon — then the privilege against self-incrimination also disappears. “If the witness has already received a pardon, he cannot longer set up his privilege, since he stands with respect to such offence as if it had never been committed.” Brown v. Walker (1895); see also, e.g., Nixon v. Sampson (D.D.C. 1975) (yes, that Nixon). (Remember that, as with President Richard Nixon, a pardon can preclude future criminal prosecutions, and not just erase past ones.)

There's more than that, including the option to refuse a pardon to preserve one's fifth amendment rights, but the article is surprisingly short and succinct. Worth a read.

And you can be sure that while prosecutors are thoroughly aware of this, it may have escaped Trump entirely.