The worker said anybody who believed Smith's management style was just old-fashioned or demanding should think again.
"It was pretty bad when I was there," he told the Herald today.
"I'm from a working-class, old-school family and you don't treat people like that."
He said even demanding or old-fashioned managers knew better.
"They don't treat them that poorly. They don't treat them like disposable pieces of trash."
He said when he asked to work from home in a different city during the 2020 national Covid lockdown, the MP accused him of being a kid running back to "mummy and daddy".
Smith denied using such language.
The former MP was also accused of having meltdowns and telling the worker: "You're the f***ing secretary. This is such an easy job."
The former staffer said Parliament must do more to protect people from abuse. He said he was effectively blacklisted because he did not just disappear but instead chose to stand up to an MP.
The former staffer has since found work elsewhere.
"With Nick in the building and me ... There's no way we could both be in the building at the same time."
Smith previously said the staffer swore at him and refused to carry out reasonable requests when asked.
And today he said was disappointed a confidential report with "errors" was released, and an incident for which he'd already apologised multiple times had since been embellished.
He added: "The final report did not make a finding of bullying."
Of the incident sparking the complaint, he said: "I immediately apologised when the incident occurred, regret it and have also apologised publicly many times."
Smith said more than a dozen staff worked for him during his three-decade career, most of who have become lifelong friends.
He said one Parliamentary Service employee who worked with him "for 26 years" told him she couldn't recall a time Smith ever swore or raised his voice.
Smith told the investigator of the yelling incident: "I opened the door and said in a loud voice that I wanted some quiet and it was a professional environment."
The MP rejected a claim his spit landed on a woman during this incident.
Another witness said Smith's behaviour in that incident was frightening, unreasonable and unnecessary.
'You're an embarrassment'
In a draft investigation report, a witness told an investigator Smith yelled and screamed at the staffer.
"She felt Nick was losing the plot, but she also felt standing up to an MP was not easy.
"He's just screaming, saying: You're an embarrassment," the witness told the investigator, according to the draft.
McCarten said the staffer's lawyer told him the draft was in "all material respects" unchanged from the final report.
The draft said there was evidence the health and safety of an employee was or may have been placed at risk due to Smith's conduct or behaviour.
The worker told an investigator he "was always trying to make it work and he kept hoping that he could find the nice version of Nick".
The draft added: "He never talked with Nick directly about his concerns because it would have got nowhere."
The staffer said Smith over-reacted to chatter near his office by shouting loudly. The worker said the outburst was "horrific" and he left the building for the day.
Two weeks after the witness lodged a complaint in August last year, Smith's counter-claim drew the worker into the drama of a joint investigation, McCarten said.
"The investigation went on for eight months. The worker had to be available at all times over something he never asked for."
McCarten claimed Parliamentary Service chief executive Rafael Gonzalez-Montero did not do enough to protect or support the young staffer.
He said the worker had since found it impossible to get jobs in Parliament.
"The young worker was thrown under the bus through negligence and lack of care. He was blacklisted."
McCarten said the chief executive pledged to protect the young man's career but instead there were "whispers around the dark corridors".
McCarten said Parliamentary Service started paying for the worker's lawyer but then stopped. "He's in debt now because of that."
Gonzalez-Montero felt bad about what happened but had done nothing to make things right, McCarten said.
In May 2019, the Francis review into bullying and harassment found a toxic culture had reached virtually every part of Parliament.
The review said bullying and harassment were systemic, involving harmful behaviour by and between staff, managers, MPs, media and the public.
Inadequate pastoral care was among risk factors for bullying and harassment, the review found.
"We are committed to continuing to implement the recommendations from the Francis Review and contributing to achieving a healthy workplace culture at Parliament," a Parliamentary Service spokeswoman said today.
"The Parliamentary Service does not comment on employment matters particularly when employment claims have been made that are outstanding," she added.
"It's my understanding that there is a possibility of legal action and therefore it is inappropriate to comment," Speaker Trevor Mallard said.
Witness loses faith
A witness who complained about "aggressive bullying and intimidation" from Smith said she had lost faith in Gonzalez-Montero.
"Raf promoted an open-door policy and encouraged staff to boldly speak up if ever they saw something they believed needed reporting," she said in a statement from July, sent to the Herald.
She said this was why she reported "aggressive bullying and intimidation" from Smith in July 2020.
"The fact I am writing about the situation more than a year later shows just how poorly this has been dealt with."
'Demanding and direct'
Smith described his management style as "intense, very productive, demanding and direct".
Another worker interviewed said Smith could be challenging but the role needed an older person with more life experience and more initiative.
Smith earlier this year was the longest-serving MP. He won seats in Tasman and Nelson 10 times and was elected as a list MP in 2020.
At one point he was the National Party's third-highest ranked MP. In June this year, he announced his resignation, citing an inquiry into a "verbal altercation" in his office.
