The delay caused by the five minutes process of getting Lee Harvey Oswald a sweater allowed Jack Ruby time to arrive. If Ruby misses Oswald then I assume he survives to face the two murder charges ( President Kennedy and Officer Tibbet) I just reread Gerald Posner's Case Closed, which describes the facts of the Kennedy assassination. The evidence against Oswald was well beyond a reasonable doubt. The rifle found on the six floor of the School Book Depository with his fingerprints on it. The witnesses that said the shot came from the sixth floor of the Depository. The two witnesses that saw Oswald shoot from the sixth floor. The five witnesses that saw him kill officer Tibbet. The fact that he left work. The witnesses that saw him hide from the police in a shoe store lobby.The two witnesses that saw him run into a movie theater without buying a ticket. So would he get a plea bargain? Could a judge give him a plea bargain without angering voters who want Oswald strung up? If he avoided the death penalty, how long does he last in prison in the isolation of protective custody? Would he at age 73 by still alive in prison or in some prison mental ward?
If convicted, death is the sentence. Now to the defense, first there are two crimes.
The officer Tibbet has multiple witness, Oswald caught with the gun. Very easy case. But to the eyewitnesses, since they have him traveling multiple routes to the crime scene, it shows eye witness make mistakes. This would be useful in the defense of the Presidential murder.
JFK - Oswald could go insanity defense or did not do it defense. Two people have been acquitted of trying to Murder the President (Reagan and Jefferson), so don't rule out his working. And he did enough strange things that one could do weeks and weeks of bizarre things Oswald did to build the defense. IMO, the government would prefer this defense. Now to the evidence. He can use all the great stuff provided by the various conspiracy theories, their evidence, and their witnesses. The defense will be able to call every last one of these people to testify, and likely some high end defense team helps Oswald. The preparation will be massive, so they trial could easily be 5 or more years after the shooting. And the appeals on each of these issue could last 10 years or more. No to the evidence that hurts and helps him.
1) The rifle. People use pictures and a mark on the rifle to say it was his rifle due to a nick. Probably true, but a good defense team will throw doubt on the nix or claim evidence tampering. Or just claim the gun was stolen. He lived in a boarding house, so easy to claim. Oswald may need to testify on this item.
2) Palm print: It is on a funny place to hold your hand on a gun, the center of stock. First, if we use stolen gun defense, then yes it is his hand print, but before it was stolen. Or he can claim the cops force his hand to touch the gun after he was arrested. For second one, he needs to testify. Hard to do, unless he can get the officer trial in a separate trial. But if he does testify, it is the most interesting testimony of the 20th century. Even today, I can't excluded that the palm print was not after Oswalds death or while he was in custody. Evidence tampering is too common in high profile crimes, or what is better called Evidence enhancement, where the cops are sure they have the right guy, but need a little buff on the evidence.
3) Witnesses with Oswald in Window. Easy to neutralize. Just bring in all the other witnesses that saw other things to neutralize. Also, from that distance, any positive ID is questionable.
4) He left work - Weren't the cops clearing the building to search it. He was calm passing the cop who talked to him. Also, a good explanation is that he was afraid, so left the area. If I thought there was an assassin in my building, I would not stay in it.
5) Hide in shoe stores - again easy. First, he is paranoid. Second, president was assassinated. Three, bring in all the other confusing statements by witnesses who went on news to say what they saw.
It would have been a very interesting, hard case for the state. And all the police mistakes that people use in the conspiracy theories would be useful. No tape of the time he was interviewed with police. The way the secret service stole the body at gun point from the Texas hospital. You may lose chain of custody right there. The body not being preserved for the defense to do its own investigation. May lose autopsy right there, and have the prosecution limited on what it can use in trial. For example, if the defense claims the body with the Zabrudor films shows the shot was from the grassy knoll, and their is misconduct by the state, the judge might throw out the prosecution ability to even claim the shot came from the building. And these types of issue will drag on, because each item will be ruled on, emergency appeal, then reappealled after the trial, and we easily could have several trials. A lot depends on does the judge want a quick conviction or does he want to demonstrate the protection of the USA legal system to the world. Remember, each day will be cover in Pravda and this is both an internal and an international trial that impacts the view of the USA world wide. While I think a conviction is very, very likely, it is not guaranteed.
Now the only way I could see a plea is if the judge starts tossing evidence, or allows too many conspiracy theories to be used by the defense. For example, if the state believes the judge may impose sanctions on the highly irregular autopsy, then the state might cut a deal before or after the ruling to avoid embarrassment. For example, the state might go to Oswald lawyers an say, we will not oppose an insanity defense. The other thing would be if Oswald was involved in a conspiracy. When people think of conspiracies, they think of S.P.E.C.T.R.E from the bond movies, but a conspiracy can be as simple as someone else had preknowledge he was going to try to assassinate or someone paid Oswald to do the killings. And even if this was not true, Oswald might take the stand and make stuff up.
Now before people scream conspiracy theory, I am not saying I can show anyone helped him. I am saying under the USA legal system, it would be hard to prove beyond a reasonable doubt that they did not happen. For a hung jury, Oswald just needs one juror to believe, hey, the shot did come from the grassy knoll, it can't be Oswald. And since if separated trials, the officer conviction is probably done, they just might execute Oswald for the Texas trooper and forget the retrial.