Wild Nate theory...

I could be way off with the timing abd remembering everything but my Missus just said she really thinks it was Moira who accidentally shot Nate and John volunteered to dispose the body only Moira has no recollection....

But then I thought hang on....

Anybody remember that episode when Ross had the gun in the barn to scare any intruder and let a shot off but it was just his son in the barn? What if that shot killed Nate by accident with Ross finding out hours later and panicking and dumping the body, keeping the phone to keep up the pretense Nate is alive i.e. Frankie's present

Or had Nate already left at this point and my theory is not possible