Watching the limited video and reading the deluge of info released thus far ...
This seemingly started with poor judgment, and went downhill.
No way for me to pretend to know the father's experience and professionalism as a former police officer and retired DA's Investigator, of course.
That said, being a retired peace officer, it's dismaying to think he would've thought it was any sort of a good idea to arm himself, and encourage (?) his son to arm himself, and
chase after a man seen running for what he might think would be nothing more than a low level property crime. That's why we pay local taxes to have the uniformed cops drive around and be willing to check out suspicious people and circumstances.
Maybe stretch it and follow
at a distance, and not stand with a gun in the bed of the truck, so he could offer to update the responding cops to DoT? Even that's a recipe for a possible nasty turn of events, though. Let the responding cops have the room to do their thing.
A little while back I had a neighbor come over and get me because another neighbor's house alarm was going off in the afternoon. Yes, she knew I was a retired cop, so she came to knock on my door. "Did anyone call the sheriff?" Yes? See anything obviously bad? No? Then I'll walk along, but only to observe from a distance, and try to keep everyone else to stay back and wait for the sheriff.
Local deputy rolled up, after driving right by the right address. (Hey, it happens, folks.)
I met him in the road, identified myself and my little "group" as concerned neighbors, and pointed out the correct residence (visible from our position about a hundred yards away). Gave him what little succinct info we had about the new buyers to the neighborhood.
Since he was alone on the call, at least at that time, I quietly identified myself as a retired cop. He wouldn't have been able to see my pocketed weapon (and he didn't ask), and neither did any of the neighbors (be able to see, or think to ask). I offered to make sure the rest of the neighbors stayed well back, and stood closer where I could have a good view of 2 sides of the house/property while he did his check for open doors, windows, people, etc ... and be able to greet any further cover unit and direct them (in case they missed the SO veh parked on a side private road

).
Anticlimactic. That's
always a good thing.

House secure and no signs of forced entry. Just another new resident alarm system call in the country. Nice to have interested neighbors, though. As long as none of them do anything stupid that gets them hurt or in serious trouble, or anyone else hurt.
Oh yeah, make sure the sheriff has been called before you come knock at my door. Saves me from having to do it and play catch up/go-between. Embarrassing. Sigh.
Some people seem to want to treat property crimes like it's life and death, and don't seem to grasp that poor judgment and bad decisions can turn an otherwise low level susp/circ call into a serious injury or death event.