All it takes is a look at the forensic evidence and apply common sense.
What "forensic evidence" are you talking about?
Can you prove that there was a rifle in Ruth Paine's garage on 11/22/63 and that Oswald took it? No, you can't!
Common sense is just another way of saying "I don't have evidence, but my speculation is good enough".
The bag had Oswald's palm and fingerprint on it.
Did it? And if so, Oswald's prints are also all over Frazier's car. Does than mean he owns that car? I'm sure you can make a "common sense" argument to "prove" it does!
It contained fibers that matched the blanket Oswald used to store his rifle in the Paine's garage.
There is no such thing as matching fibers in forensic science. "Look similar" is the best you will get and that's simply not good enough.
I'd love to hear a plausible alternative explanation for the known evidence from you but I know I won't because there isn't one.
And there is the classic LN's "I'm right unless you can prove me wrong" BS.
Why in the world should anybody have to present a "plausible alternative explanation" when you can't place a rifle in Ruth Paine's garage on 11/22/63, when you can't show that it was the same rifle that was found at the TSBD and when you can only speculate about what was in the paper bag Frazier saw Oswald carry. A paper bag btw that Frazier too this day still says wasn't big enough to contain a broken down rifle.
Just like every other LN you are all over the place and confuse assumption and speculation with actual conclusive evidence!
This is a classic example of conspiracy hobbyists making excuses to dismiss the damning evidence of Oswald's guilt. They can't explain the evidence to make the case for Oswald's innocence so they try to explain it away. One of their favorite ploys is to attack each piece of evidence individually rather than look at the body of evidence as a whole. When you do the latter, there can be no other plausible explanation than Oswald brought the rifle to work and used it to kill JFK.
You ask why anybody would have to present an "alternative plausible explanation". Well, if you want to make the case for conspiracy, that would be nice. I'm not even asking you to prove how it happened. Just tell us another way it could have happened. There simply is no plausible alternative. if there was, some conspiracy hobbyist would have found one after 62 years. But of course, there is no plausible alternative to the conclusion that Oswald was the assassin.
I've served on four juries, two criminal and two civil. In each case, the judge instructed the jury to make logical inferences from the evidence presented.
This is how that process would apply to the JFKA.
Given that:
3 shells were found at the location where a shooter was seen and
a fragmented bullet was found in the limo and an intact bullet was found at the hospital where the shooting victims were taken and
all the shells and bullets were positively matched to a rifle found on the 6th floor of the TSBD and
the rifle had Oswald's palm print on it and
there were fibers on the butt plate of the rifle that matched the shirt Oswald was wearing that day and
and a bag was found near the shooter's location with Oswald's prints on it and fibers matching the blanket in Ruth Paine's garage and
Marina said Oswald kept his rifle wrapped in the blanket in Ruth Paine's garage and
there is a paper trail establishing that Oswald bought the rifle by mail from Klein's Sporting Goods Co. and
there were pictures taken of Oswald with the rifle and
Oswald's fingerprints were found on the boxes stacked at the shooters window oriented as they would be if he was facing down Elm Street
the ONLY logical inference that can be made is that Oswald brought the rifle to work and assassinated JFK with it. And we haven't even talked about the evidence that he killed Tippit.
No one piece of evidence by itself proves Oswald's guilt but collectively, the body of evidence leaves no doubt. The case against Oswald is greater than the some of its parts. It is absurd to think you could have all that evidence pointing to Oswald's guilt if he were actually innocent. That is how logical inferences are arrived at. An alternative explanation might be plausible for any one piece of evidence, but when you have to stretch for alternatives for each and every piece of evidence, reasonable doubt vanishes.
Since you brought up Frazier's description of the bag, Frazier never measured the bag. Tbe bag was measured by investigators and found to be long enough to hold a disassembled Carcano. Frazier could only estimate the size of the bag by glancing at it over his shoulder. At the time he saw the bag, he would have no reason to think the size of the bag would become important. The estimate he gave was based on memory. He was not asked to estimate the size of bag when he was observing it. But just for grins, let's say that the bag found in the TSBD was not the same bag Frazier saw. We can make two logical inferences from that. One is that the bag Frazier saw Oswald bring into the TSBD disappeared without a trace, despite a thorough search of the TSBD. The other is that at some other time, Oswald brought a different bag into the TSBD and that bag was long enough to hold a disassemble Carcano rifle.
If juries routinely applied the same thought process to the evidence in other criminal cases that conspiracy hobbyists apply to the evidence against Oswald in the JFKA, few if any people would ever be convicted. If they dreamed up the kind of silly excuses that conspiracy hobbyists do to disregard the evidence of Oswald's guilt, every criminal defendant would walk. There is no reasonable doubt of Oswald's guilt in either the murder of JFK or the murder of JDT. To anyone who is famliar with the evidence against Oswald and is capable of thinking logically there is no doubt at all.