The first part of Smerconish's show this morning was about the Minnesota shooting. He looked at it from the position of what the use-of-force guidelines are for the ICE agent. That is the standard against which the incident needs to be evaluated. He talked a bit about CBP and ICE guidelines and also those of various local (non-federal) police departments. Sort of "generally accepted practices".
Here are a couple of documents on use of force. One is for ICE, the other for CBP.
ICE (see policy statement on page 62): https://imlive.s3.amazonaws.com/Federal Government/ID255426897069329047495080324203699905714/2.2.1_Attachment 21 - ICE Firearms and Use of Force Directive and Handbook.pdf
CBP: https://www.cbp.gov/sites/default/files/assets/documents/2021-Jul/cbp-use-of-force-policy_4500-002A.pdf
It will be interesting to see if these suddenly get updated. I've downloaded both; I'm sure lots of other people have, too.
I'll post a link to the show later if it shows up online. He also interviewed someone who is an expert witness in cases like these.