Christie, who believed he was battling brain disease brought on by numerous concussions he suffered during his playing career, died in Nelson yesterday, aged 39.
It is being reported as a suspected suicide. The death will be referred to the coroner.
His death comes two years after that of his close friend and team-mate, Billy Guyton.
Guyton, who suffered multiple concussions during his playing career, died in a suspected suicide in May 2023.
His father, John, told the Otago Daily Times he was devastated by the news.
"It’s a bloody sad day. It just brings it all back," he said.
"New Zealand Rugby say players’ welfare is their priority. Well, how can it be a priority of theirs when they’re not acknowledging these head injuries?
"It’s a bit hypocritical, I think.
"Something needs to be done. How many more people have got to die?
"How many more have got to take their lives before New Zealand Rugby is actually going to acknowledge it and actually help them?"
New Zealand Rugby was approached for comment, but had not responded by deadline.
Christie played 29 games for the Highlanders between 2014 and 2017 and was the co-captain in 2016.
The loose forward returned to the club as a defence coach in 2021 and 2022.
He was forced into retirement in 2018 following a series of concussions.
The fearless defender continued to struggle with concussion symptoms and spoke out about the dangers of head injuries in rugby.
He believed he had chronic traumatic encephalopathy (CTE), the same brain condition diagnosed in the post-mortem of Guyton.
CTE is a degenerative brain disease. It can only be diagnosed after death.
The symptoms include aggression, memory loss, paranoia and depression.
Christie had talked about becoming delusional, paranoid and manic.
He also experienced anxiety, fatigue, had suicidal thoughts and his behaviour became increasingly erratic.
Christie had pledged to donate his brain to the New Zealand Sports Human Brain Bank to further research in the area.
He argued there was a definitive link between contact sports and CTE and the narrative that further research was required before conclusions were drawn protected sporting bodies "while leaving injured players to grapple with confusion, emotional pain and daily struggles".
John Guyton said he spent a lot of time with Christie in the two years since his son died.
"He’s such a strong advocate for the CTE, the head injury.
"He pretty much went through the same thing as Billy."
Christie started the Billy Guyton Foundation in Nelson, which aims to educate and help those with head injuries.
