A woman in an adjoining unit escaped unharmed, as did seven other residents in nearby units, and a wake-over trust staff member.
The centre opened about 18 months ago, and Mr Hall had been a resident for most of that time, although he was removed for a period last year after a staff member was assaulted.
While Mr Hall was diagnosed schizophrenic in the mid-1980s, he had issues while at Colenso High School (now William Colenso College) in the early 1970s.
"I didn't think he was coping that well, and because of that I think he was a bit frustrated, and he became a bit anti-authority then," a contemporary at the school said.
In his wheelchair in recent years, Mr Hall was frequently seen in such thoroughfares as Hastings and Latham streets, and at times needed to be helped to free the wheels as he tried to traverse railway level crossings.
Sources haven't confirmed that the dead man was not near his wheelchair, but those who knew Mr Hall over the years said at least partial use of one leg meant he had limited mobility without the chair.