Telling a witness he was wrong about his observation does not equate to pressuring him to change his story. The FBI knew the shots had not come from the GK and they told O'Donnell that. If he decided to alter his testimony, that is on him.
You don't quote Kenny O'Donnell. You quote Tip O'Neill quoting Kenny O'Donnell so we don't know how O'Donnel actually described the encounter. You are describing your impression of the impression O'Nell got from what O'Donnell said. A hearsay account hardly establishes that the FBI "pressured" O'Donnell to change his story.
So I'll ask my question again. Why would the FBI pressure O'Donnell into changing his story.
The more fundamental question is, were any shots actually fired from the GK. There is no forensic evidence pointing to a shot from the GK. There were no eyewitness to a shot from the GK. There was an eyewitness who had a perfect view of the are behind the wooden fence when the shots were fired and he saw no one there. The only "evidence" of shots from the GK are the impressions of a group of earwitnesses who said all the shots came from the GK. They are contradicted by another group of witnesses who said all the shots came from the direction of the TSBD. The latter group is corroborated by 3 spent shell found in the sniper's nest and the murder weapon found elsewhere on the same floor. No corroboration for the earwitnesses who thought the shots came from the GK. That includes Kenny O'Donnell.
Ken O'Donnell denied the allegations that he changed his testimony under pressure from anyone. He told the Chicago Tribune in an interview that they were "an absolute, outright lie." And Dave Powers, also quoted by O'Neill, denied the story as well.
I'll be lazy here and quote Wikipedia on this:
"In their memoir of Kennedy, Johnny, We Hardly Knew Ye, both O'Donnell and David Powers reported hearing only three shots and did not offer any speculation as to their origin.[12] According to a June 15, 1975 report in the Chicago Tribune, an unnamed "Central Intelligence Agency liaison man" told Congressmen that O'Donnell and David Powers had initially told assassination investigators that the shots that struck Kennedy came from a location other than the Texas School Book Depository, but that the two men were convinced, reportedly by FBI Director J. Edgar Hoover or his main aides, to alter their accounts to the Warren Commission to avoid the possibility of revealing the CIA's plots to kill Fidel Castro which might result in an international incident.[12] During a telephone interview, O'Donnell said he testified truthfully and called the allegations "an absolute, outright lie."[12] In his 1987 autobiography Man of the House, former House Speaker Tip O'Neill wrote that he had dinner with O'Donnell and Powers in 1968, and that both men indicated that two shots were fired from behind the fence on the grassy knoll at Dealey Plaza.[13] According to O'Neill, he pointed out to O'Donnell that he gave different information to the Warren Commission, and O'Donnell replied: "I told the FBI what I had heard, but they said it couldn't have happened that way and that I must have been imagining things. So I testified the way they wanted me to. I just didn't want to stir up any more pain and trouble for the family."[13] However, Dave Powers denied such conversation and claim occurred and criticized his autobiography.[14]
Again, O'Neill's allegations were denied by both men.
See here:
https://news.google.com/newspapers?id=lQhIAAAAIBAJ&sjid=TQANAAAAIBAJ&pg=1934%2C3948488&hl=enThis is another example of how Michael Griffith uncritically accepts information that supports his pre-determined conspiracy view. And it doesn't matter whether it contradicts other claims he believes. Remember again he believes in the acoustics evidence that concluded three shots were fired from the TSBD and another shot came from behind the fence. But he quotes allegations that O'Donnell said the shots came from in front of the limo. That is, of course, completely at odds with the acoustics analysis. But he doesn't care.