In the case of Prince Andrew [1], there was a private settlement with the victim with the strongest case. He did not (directly) admit guilt and got his case closed.
> If the private settlement includes a gag condition for the primary criminal witness….
A civil settlement cannot include a condition prohibiting someone from testifying or otherwise cooperating with a criminal investigation, and one which purported to do so would be void.
> Is it legal to enforce an NDA that covers up a crime?
Not only would such an NDA be unenforceable, offering (in so far as that implies a threat to enforce) and even moreso directly threatening to enforce one for that purpose (leveraging the other parties lack of knowledge that it was unenforceable or fear of the consequences of a lawsuit even without merit) would seem to be witness tampering, a separate crime.
One theoretical example, would be something like $1mln/yr paid in weekly installments, conditional on no details she knows ever being known by anyone else.
If approached by a cutout attorney (using attorney client privilege and on behalf of ‘anonymous friends’), payments from blind trusts not associated with the royal family, and a couple layers of that most of it offshore, and only a very determined investigation with a lot of international pull is getting anywhere. And the signs are pretty clear, that isn’t happening in a case like this.
The incentives are aligned such, that I doubt such an agreement would even need to be written down.
With the connections and pull within the gov’t the royal family has, any attempt to even track it down would likely get someone shut down, even in the FBI or CIA. But maybe I’m just imagining things.
Prince Andrew; to my knowledge, no Prince Albert has been connected with Epstein.
> there was a private settlement with the victim with the strongest case.
In theory, a private settlement of civil charges does not protect against criminal charges arising from the same conduct.