Right after the FBI told Johnson they had no intent to arrest him for anything -- they just wanted the truth on record -- Johnson set right about lying.
Here are some highlights from Johnson's description of the Ferguson Market robbery:
"Now, there was an incident at Ferguson Market where the cigarellos, not cigarettes, cigarellos were by law stolen but not in a manner where it was forceful, or ya know, a weapon was drawn." (page 7)
"He went back again to grab some more cigarellos. But again, it was like reaching into your own cabinet, 'cause it wasn't a snatch and grab." (page 8)
"The store clerk did come around and just stood in front of the door and kinda held his hands up in a stop motion. My friend, Mike Brown, he didn't wrestle or punch the man or pull any weapon out on him. Man, he put his hand on him ... one hand, and just moved him out the way. The man kinda stumbled over and we continued to walk." (page 8)
Later, when the questioner revisits the robbery Johnson claims he thought the theft was just a prank:
"The whole store. I thought the whole store was in on a prank. Because, like I said, he didn't snatch and grab." (page 53)
"The clerk swatted, but it wasn't even in a fast motion. It's like, how you smack a baby hand (demonstrates). And I almost could not understand why it was so soft. Like, somebody's trying to, I mean, if he's really stealing from you you should try to do more to stop somebody." (page 54)
And one last time the questioner reviews Johnson's account of how he and Brown left the Ferguson Market:
"[The clerk] tried to stand in the way. Big Mike asked "Could you get out of the way?" And he's still standing there. And Big Mike doesn't forcefully, he just, like I said, if it was forced the man was so small I know if it was forced he would have hit the ground. He would have fell." (page 72)
Thus ended the FBI interview. The details of The Tussle and The Turnaround and The Shooting don't get any more accurate than the robbery account.
The FBI has known since that August 13th interview that their star witness can't tell a straight story about what he and Brown did the day of Brown's death.