The government is now admitting that he lied in the stand with their knowledge - the government suborned perjury to get the conviction in other words. He portrayed himself as a "mule" someone who'd been hired to make a one-time run, wheras he is a habitual smuggler who probably WAS armed.

Thus my thought that they should have shot him dead. Then they would probably have recovered the weapon.

The only thing these agents did wrong was to not report the shooting, probably because they knew they'd get railroaded.