Evidence gathered in a criminal investigation is typically not released to the public except those materials that are public or government-owned (sometimes you'll see autopsy reports, death certificates, 911 calls, body worn cam footage made public). Are you saying they have to produce the bodies to the public so the official government documents like the autopsies or death certificates can be believed? I have no knowledge of that ever happening at least not in the modern era. Had there been a trial, that would provide an opportunity for the public to view evidence but when there's no trial they don't usually just put on a show of their evidence to the public (for a number of good reasons).
Materials in a criminal investigation file can be requested through the state FOIA process, but when it relates to private material seized in the investigation (as opposed to materials created by the investigation) there are often criteria that keep them withheld, for example if the owner objects on privacy grounds. As intriguing as this case is, it's a single murder between two private citizens. The true "public interest" in access to the private material is very low.