Eva Grant is Jack Ruby’s sister. In being questioned about her brother killing Lee Harvey Oswald, she talks about these photos that Jack took of leaflets that say;

“IMPEACH EARL WARREN”

There is a P.O. Box on them that Jack looked into and saw that it was crammed with letters. I believe the billboard above is the image Eva describes. Jack was in a rage over this image. Later on he would claim the Jews of the world were under attack, and once again, are being wiped out. This questioning of Eva does not reveal that the John Birch Society is responsible for this billboard and the pamphlets.

http://jfkassassination.net/russ/testimony/grant_e1.htm

Here is a recording of a conversation Johnson had with Senator Richard Russell where he informs him he has no choice but to serve on the Warren Commission, because there are ramifications that involve Khrushchev and Castro that might lead to…