Tracey Donnelly is not sure if she should think her husband is alive or dead.

On June 21 it will be a year since her husband of 14 years, metals scientist Jim Donnelly, disappeared virtually without a trace from the Glenbrook Steel Mill south of Auckland where he had worked for 20 years.

His cellphone and bank accounts have not been touched and his disappearance is puzzling and out of character and has devastated his wife and two young children.

The Donnellys were considered a typical New Zealand family and friends said Mr Donnelly, 43, was a good father and husband.

Six months after he vanished Mrs Donnelly said there was nothing to suggest he was alive or dead.

Now, as the first anniversary of his disappearance approaches, family friend Clayton Hills said nothing much had changed. The family still had no idea what had happened.

Mrs Donnelly held some hope for her children that her husband was still alive.

"If she was on her own, she most probably would [think he had died].

"She has got the kids and it is harder for them to understand. It makes it harder to cope with."

Mr Hills said that if anything had been troubling Mr Donnelly, the family would have expected that to have been resolved after nearly a year.

If he had decided to go bush or take time out, he would have needed help.

"Without people's help you realistically can't do that. I know from speaking to police ... They have always known within a period somebody is still out there."

Shortly before Father's Day last year Mrs Donnelly released a personal and emotional letter from the couple's 8-year-old son, Liam.

"To my Daddy, wherever you are ... We miss you lots and lots. It's nearly Father's Day and can you come home please?" Liam said in his letter.

"We are buying you a present, but it's a secret. Mummy is making a box to hold them in case you have forgot the way.

"I will try not to be too disappointed if you don't, but I'll wait all day."

That letter produced no leads.

Mrs Donnelly said last September, after her husband missed Liam's birthday, that it had been wishful thinking to expect him home for his children on Father's Day.