His autopsy was not illegal. The Secret Service officers suspected that the assassination was the result of a conspiracy. A conspiracy would have made it a Federal crime. They were justified under Title 18 , Part 1, Chapter 19 of the US Code in removing the body from Dallas.
Hahahahaha so a LNer uses a conspiracy when it suits him hahaha
They didn't suspect they knew, they drove him into the ambush, slowed down and removed protection and ignored rules about vehicle speed and high rise buidings with windows open.
Suspicion was not enough t lawfully do what they did that's why they had to threaten and aim to draw weapons