He said police had asked to speak with Mediaworks staff as part of the investigation.
"However, these requests were declined, so Police took the steps necessary to obtain the information required to progress the investigation, including the execution of search warrants."
READ MORE:
• Did she find a loophole or simply break the law?
The identity of the person or people who filled out the mail order form used to buy the .22 rifle at the centre of the Story current affairs broadcast will be key to the police investigation.
Du Plessis-Allan spoke to her Story co-host Duncan Garner the day the story broke on TV3 and told him those who worked on the story knew it "was likely to land us in a spot of bother with the cops".
She described how the rifle was bought using a mail order form which was downloaded from the internet, filled out with bogus details and sent to Gun City.
She claimed the sting exposed a "massive loophole" - and TV3 owners Mediaworks have since described it as important "public interest" journalism.
The search warrant used by police when they went to du Plessis-Allan's home in Wellington stated that it had been obtained as part of an investigation into forgery and "obtaining by deception" - carrying sentences of up to 10 years and seven years in prison.
Ex-judge criticises search
A retired long-serving district court judge has criticised police for their treatment of television journalist Heather du Plessis-Allan, who is under investigation after purchasing a gun without a firearms licence as part of a news story.
Roy Wade said he "very much" doubted whether there was a need for police to rifle through the journalist's private space and belongings, given the nature of the investigation.
Yesterday police executed a search warrant at the Wellington home du Plessis-Allan shares with husband, Newstalk ZB journalist Barry Soper.
READ MORE:
• Heather du Plessis-Allan: 'The police went through all my stuff'
The search came after an expose by du Plessis-Allan for TV3's Story programme. She collected a rifle from a courier after sending Gun City a mail order form in which the "Police Use Only" section had been filled in with a fictitious officer's name and police registration number.
The form included details of the credit card used to pay and a firearm licence number, apparently checked as genuine by Gun City staff.
Today Mr Wade, who presided over cases in the Auckland region, wrote to Commissioner Mike Bush expressing concern and "sadness" over the handling of the investigation and search warrant (scroll down for full text of letter).
He revealed he first met Mr Bush 21 years ago when the then-sergeant arrived on his doorstep at 5am with a search warrant.
Mr Wade said that warrant was erroneous and appealed to Mr Bush to think hard about the decision to search du Plessis-Allan's residence.
"Search warrants are inherently obtrusive: how would any one of your staff (or you, for that matter) like to be subjected to seeing their most intimate belongings and documents pored over by total strangers for no reason at all?" he asked in the letter seen by the Herald.
Mr Wade said the police had done themselves "great harm" by their "insensitive treatment of the citizens of this country".
Mr Bush did not comment on the investigation into du Plessis-Allan. However he did respond to Mr Wade's letter.
"I have known Mr Wade for more than 20 years and hold him in the highest regard, so will be making contact with him personally in due course to discuss the issues he has raised," Mr Bush told the Herald.
"In relation to the search warrant 21 years ago, police did knock on the door and speak with Mr Wade, who had just recently moved in. However, it was quickly realised that the people we were looking for were no longer there and the warrant was never executed."
Du Plessis-Allan posts handwriting sample on Facebook
Meanwhile, the journalist at the centre of the scandal has taken to Facebook to thank her supporters.
While police searched every corner of her home for a handwriting sample yesterday, Heather du Plessis-Allan posted a photograph of a written note on her Facebook page.
"Hey, thank you all for the messages of support today," she wrote.
On Story last night du Plessis-Allan, who hosts the show with Duncan Garner, spoke about the search warrant.
"Here's my question - they want my handwriting, why didn't they search my desk, full of bits of paper I've written all over?" she questioned.
"Instead, they found almost nothing at home.
"I am just standing by the story that we did. It was good journalism and this will not stop us from doing good journalism on this show."
Full text of Roy Wade's letter
Dear Mike
As we both recall, we first met 21 years ago when you banged on my door at 5am armed with a search warrant. You were a Sergeant in the Takapuna Drug Squad and I was a recently appointed Crown Prosecutor.
Fortunately, I had just finished a High Court trial that involved your junior who came with you and who was able to explain that an error had been made.
Today, I saw that your officers thought it prudent to search the home of a reputable journalist who did nothing more than expose the hopeless inadequacies of our gun laws.
Search warrants are inherently obtrusive: how would any one of your staff (or you, for that matter) like to be subjected to seeing their most intimate belongings and documents poured over by total strangers for no reason at all?
If your officers did really need a handwriting sample (which I very much doubt, given that she always acknowledged being the author of the form in question), why not simply ask for one? Was it simply to try and humiliate her?
The Thorpe Enquiry 20 years ago highlighted the complete inadequacy of NZ gun laws. It was launched to address the gaping holes in our legislation. It cost millions but was totally ignored.
Was this a precursor to the flag referendum?
The NZ Police do themselves great harm by their insensitive treatment of the citizens of this country.
The revelations of the last few days concerning the way the NZ Police release and censor the statistics only add to our concerns.
I write this with great sadness; I spent much of my career prosecuting crime and I have family who serves in the UK Police. I count many of your officers as personal friends.
Please think again!
Kind regards
Roy Wade
