Wow. A polygraph does not work like a crystal ball discerning what actually happened. At best, it measures whether an individual knows they are not telling the truth. If Frazier honestly, but erroneously believed this wasn't the bag then he would be not be lying in his own mind even if he was wrong. He would be mistaken but not lying because he would believe he was telling the truth. That doesn't tell us that Oswald did not carry this bag but that Frazier didn't believe it was the same bag.
Granted.
Now do you have any evidence
at all that CE 142 was the bag that Frazier and Randle saw?
The "desperation" here is your own and not that of the DPD who had enough evidence to convict Oswald a thousand times over.
No, they actually didn't. What little evidence there is, is circumstantial and tainted.