hang vs hung

(Grammar Questions I Couldn't Answer)

A colleague messaged me:

Joel, "hung by his neck" or "hanged by his neck"?

I responded:

So, I'd say this is a case where they're identical.  It's an irregular verb that is slowly being regularized over time 

He then said:

Yeah, I think hanged vs hung is more of a prescriptive rule, really. Still, I encountered this example produced by a well-read native speaker, so I thought maybe there's a minute difference because there's an object, i.e. someone is hanged but if someone is hanged by the neck then the focus is more on the action of hanging and hence it's hung ... I'm probably just overthinking things. 

I said:

There might actually be something to it. I'll add it to my list of "Grammar Questions I can't Answer"