Is the article correct in stating that pretty much all of the evidence centers around the six letters? IMHO, and apparently the FBI's too, that's a pretty weak

Is the article correct in stating that pretty much all of the evidence centers around the six letters? IMHO, and apparently the FBI's too, that's a pretty weak connection. It wouldn't be difficult for anyone, especially a CIA or FBI agent, skilled in writing forensics to point the finger at someone else.