[fixermark]

That's not how contempt works.

If the prosecution asserts you have evidence material to the case that you would be legally required to render and won't render it, and the judge believes you probably do, that's it; they don't have to prove the evidence is in your emails to search for the evidence in your emails. Fail to render up the emails or render them up in an intentionally-obfuscated form, and they can hold you in contempt at pretty much the judge's discretion (your mileage may vary depending on severity of crime and state law, where applicable).

(Personal observation: people of a technical bent seem, for whatever reason, to underestimate the wide swath of power the legal process has in investigating a murder case).