You really have only 2 choices:
1. All the obfuscatilon, the unclear or absence of autopsy photos, the rearranging of evidence, the shoddy notes taken by Will Fritz, unable to have lawyer, stenographer, present or find a recorder to tape Oswalds "interrogation" etc, is an indication of conspiracy or at the very least introduces reasonable doubt.
2. All the confusion and anomalous "evidence" like CE 399 is because of complete and utter incompetence of the investigators. And it was a consistent incompetence at every point in time, right up to the failure to provide adequate security for Oswalds transfer which led to his execution in real time, viewed by millions of people.