I’ll reserve judgement, but this looks like multiple failures to follow procedure. At least this is being investigated by an external agency.
Police should expect that residents of a house they approach are armed. They should clearly and carefully identify who they are, while staying in a covered position. You don’t just show up and demand someone lay down a weapon.
As the family attorney said this morning it not a matter of if they win in court its just a matter of how huge the award will be.