The first thing any of David Charles McSweeney's neighbours knew about the 54-year-old was that he had just stabbed his wife of 18 years to death.

"We never saw them," says one Red Beach resident, who lives metres from what, for about six months, was the McSweeneys' rented weatherboard home on Bay St.

"It's a little sad if you live somewhere and you don't know your neighbours."

But down the road in Whangaparaoa, one of McSweeney's mates is still coming to terms with what his friend did that day in April.

"He was a good bloke, Sue was a nice person. It was totally out of character," says Eddie Law.

Mr Law knew David and Suzanne McSweeney for at least 10 years. He and McSweeney and their wives went fishing together, socialised together, ate together.

He struggles to comprehend how the former cop and "average Kiwi bloke" could, in what prosecutors described as a frenzied attack, knife Suzanne up to 30 times.

McSweeney - who in his police career put the cuffs on the Rainbow Warrior saboteurs and brought Parnell Panther Mark Stephens to justice - stabbed his wife repeatedly through the upper arms and torso in the attack. He plunged the knife into her heart, then sliced her throat, cutting crucial arteries, her windpipe and larynx.

"There must have been something in there that was dark, and nasty and ugly."

Mr Law, owner of the Whangaparaoa 100% store, just can't get his head around how his generous, honest friend could be languishing in prison, staring at a life sentence for murder.

"I just keep asking myself, 'How could he do it?'

"He cut his wife's throat. It's like hundreds of people, you know, they come into the shop, you have a cup of tea, then something like this happens."

The typically clinical police summary of facts says the McSweeneys had financial problems with their Silverdale-based Creative Textiles, the scene of Suzanne's murder.

The couple had lost the equity in their home, and in the business, trying to keep it afloat.

The business was placed in receivership in May.

There were "incidents of violence" in the relationship, apparently, but Mr Law doesn't know anything about them.

"I only saw the nice sides of him. If there was [violence] it is either hearsay or parts that I missed."

As far as the Laws are concerned, Creative Textiles was a perfectly respectable business. It had "quite a good name" and they had "never heard anything bad about the business".

Mr Law has visited McSweeney in prison, and will visit him again. He will not attend the November 28 sentencing.

"It was hard for me to go and see David in jail, and I suppose it was hard for him to see me. I think he would be pretty sorry for what he did.

"You don't like to see him where he is, but you don't like to see [Suzanne] where she is."

Mr Law says he wanted to ask McSweeney "just what the hell was he thinking", but it didn't seem right.

Instead, they made small talk on a telephone through a glass partition. He left McSweeney a book on Gandhi. "He's an intelligent bloke."

The Anvil Rd site of the McSweeneys' Silverdale business has a new tenant, one that deals in "plasterboard services", according to the sign.

No one seems to know much about the couple or what happened to the business after the killing.

"It closed after that lady got murdered," says a storeman working nearby.

Around the corner a couple of the locals are having a pint at the Wade Hotel, and one has his own theory on McSweeney's actions.

"He was just a citizen who got into trouble with finance and went nuts."