Stepson Dan Herk, 36, was killed in the Pike River coal mining disaster of November 2010, and in 1990, the couple's seven-year-old son Jessop died in a car crash caused by a drunk female driver in Motueka on Mother's Day. Brett, 19, died a few years later in a fall in Auckland.
The morning after the crash which claimed Mr Hall's life, Slater wrote in a blog post: "... some feral tried to evade the police, they wound up dead by smacking into some innocent homeowner's house."
The comment led to death threats against Slater.
In his waateanews.com interview, he admitted the comment, in "hindsight", was offensive.
"You've got to put it in context. When the first story broke, the story was, that the guy who died was the driver of the car," he said.
"Now, what were the facts that we knew at that time - that he was the driver....that he had fled from police, that they were drunk and that they didn't have lights on. That's feral behaviour right?
"Those sorts of people exist in our small towns and even in our big cities, particularly in some areas down south and out west and it is feral behaviour.
"It doesn't matter who they were, none of the other detail was released until the next day," he said.
"In hindsight, yes it is offensive," he said of his post. "You hear the story with 20/20 hindsight, it does sound and look appalling.
"I wouldn't normally say that. If all of those details had been revealed at the first outset, I probably wouldn't have said that."
Slater also said he would have apologised to Ms Hall "if she hadn't rung up and given me endless abuse".
