The two men talking in the Carousel Club on Commerce Street had a shared problem: US attorney general Bobby Kennedy. It was October 4 1963 in Dallas, Texas, and Lee Harvey Oswald and Jack Ruby had a plan.

"There is a way to get rid of him without killing him," Oswald, an angry, idealistic young man tells Ruby, a club owner. "I can shoot his brother."

"But that wouldn't be patriotic," Ruby warns.

"I can still do it," Oswald tells him. "All I need is my rifle and a tall building; but it will take time, maybe six months to find the right place; but I'll have to have some money to live on while I do the planning."

The transcript of a conversation between Ruby and Oswald, less than two months before the assassination of President John F Kennedy, would be one of the most sensational revelations about an event that has fuelled conspiracy theories for more than 40 years. But there is one problem with the document unearthed in a safe on the 12th floor of the Dallas courthouse: it is almost certainly a fake.

The Guardian

"The cowboys are the crooks huh?" he asked.

"Then where's all the good guys?" he added.

"Dead!" came the reply.