The Dallas PD was either incompetent or intentionally malicious, but most of the problems with the evidence at the Book Depository and Tippit crime scenes originates from the mishandling of the case by local police. Captain Westbrook appears to have been in the middle of nearly all the problems with the Dallas PD evidence on 11/22/63.
The FBI is responsible for the post-11/22 cover-up and they no doubt got orders from LBJ and Hoover to focus on Oswald and ignore other potential leads.
The CIA and Secret Service obstructed investigations and covered up stuff too.
All of the above could be dismissed as incompetence and attempts after the fact to cover up their incompetence. I'm receptive to that argument.
However, in the big picture, that explanation doesn't explain the inconsistencies in the forensic evidence and other inexplicable stuff related to this case.
For example, how is it that dozens of witnesses between Parkland and Bethesda said they saw the back of Kennedy's head blown out but the autopsy photos don't show it? We're talking about doctors and nurses. Not lay people. How could so many of them be wrong in their description of Kennedy's head wound?
The inconsistencies with the Medical evidence are one of the main reasons I don't think we'll ever be able to conclusively say there was a single shooter.
People intuitively feel that there's more to the story and they're probably right.
"However, in the big picture, that explanation doesn't explain the inconsistencies in the forensic evidence and other inexplicable stuff related to this case." Hoover laid down the law before the investigation had really begun - it was to be demonstrated to the public that Oswald was the lone assassin.
The FBI's investigation into JFK's assassination began with this conclusion!The Warren Commission Sham was merely an extension of this pre-ordained FBI conclusion in the guise of a lame puppet show.
The Warren Commission Report is a ridiculous tissue of fabrication, misrepresentation and misinformation. This is an easily demonstrable fact.
On top of the laughably incompetent/corrupt DPD investigation, it's all grist for the CTer mill.
But none of it necessarily points to a conspiracy or cover up.
The planet had stood on the brink of World War III only a couple of years before. Now the most beloved President had been assassinated by an ex-Marine who had recently returned from Russia.
It was of paramount importance to demonstrate that this was just some random loner. The slightest hint of Russian involvement would have ignited a situation far more serious than the Bay of Pigs.
So the order went out - Oswald is the lone assassin and the purpose of any investigation is demonstrate this and nothing but this.
Whether or not he was a lone assassin was irrelevant.
Evidence was manufactured, manipulated and misinterpreted to this end. Not to cover-up a conspiracy but to avert a global catastrophe.
Further muddying the waters was the fact that 99.9% of all law enforcement officers appeared to be utterly convinced Oswald was the lone assassin as soon as he was arrested. By the end of the first day of the investigation it was deemed to be a slam dunk of a case. Altering a few details to make sure some Pinko lawyer didn't get him off on a technicality was a perfectly acceptable approach to the case. Again, not in the service of a conspiracy but as part of an utter conviction that Oswald was the assassin and he acted alone. A perfectly natural conviction.
On top of this was the rush by the intelligence services to hide the fact they had been closely monitoring Oswald prior to the assassination.
This was a very bad look indeed but a worse look was when evidence of this cover-up started to come to light. This really was fodder for CTers.
Again, actions not taken as part of an assassination related conspiracy, merely CYA on a grand scale.