Eff,
"Mr. Pretti never showed his gun."
From what I have read, Pretti had the gun on his person, but he never displayed it.
During the struggle on the street, an agent discovered the gun in his waistband or holster and removed it while others were yelling, "gun."
My personal suspicion is that the agents were not communicating clearly and that whoever fired was not aware the gun had already been removed by an agent.
Pretti had also behaved aggressively during an earlier encounter with federal agents. Bringing a gun into a volatile confrontation certainly increased the potential for confusion. Also, they had not been aware he had a gun so it came as a surprise and their training kicked in.
Does that excuse the shooting or establish that it was justified?
No.
It is just an attempt to understand what the agents may have perceived and how the situation went so badly wrong.
Truth,
"We attacked them twice within 7 months"
Why did we?