Did RFK Tell Garrison that there were guns between him and the White House?

We will start this off with a UPI story from June 11, 1968, just six days after the assassination of Robert Kennedy, quoting Mark Lane:

Sylvia Meagher wrote a letter to Kerry Thornley, and wondered if Jim Garrison would back up the Mark Lane story.

Thornley wrote Meagher back, and was anxious to write about Mark Lane.

Of course, it didn't take long for Garrison to repeat the Mark Lane story!

Here is the article that Kerry Thornley wrote.

Update

Here is a letter that Sylvia Meagher sent to David Lifton about this affair: