Your estate retains many of your rights when you die. However, the federal privacy act explicitly does not apply. Your estate may have privacy rights via the Constitution, although privacy is not specifically enumerated. Your estate may have privacy rights via state law; but that wouldn't bar the federal government from disclosing its investigative materials.

OTOH, there's a 2004 case, National Archives & Records Administration v. Favish[1], which establishes the surviving family's right of privacy to death scene photos, but that's technically not privacy of the deceased.

[1] https://www.justice.gov/archives/oip/blog/foia-post-2004-sup...