But John Key would be negligent if he confines the inquiry to one of mere ministerial responsibility.
A cache of emails appears to reveal that three people - Carrick Graham, who was former Hanover Finance director Mark Hotchin's PR man, tax lawyer and blogger Cathy Odgers (aka Cactus Kate) and blogger Cameron (Whale Oil) Slater - were running campaigns apparently on behalf of Hotchin to try to discredit the SFO and the Financial Markets Authority as they investigated the failed finance company.
For Key to focus the inquiry's sights on the narrow matter of a possible ministerial transgression when the picture is much bigger would be a travesty.
As shadow attorney-general David Parker noted yesterday in his own letter to Key, the allegations involved the undermining of the Serious Fraud Office, undermining of the Financial Markets Authority, undermining of the head of the SFO and intimidation of witnesses, including Tony Gapes, in relation to the SFO and FMA investigation into the affairs of the Hanover Group of companies and their directors.
The ringleaders in this campaign appear to be Graham (the paymaster), Odgers, who manufactured the bullets, and Slater, who was the prime publisher of their campaign on his Whale Oil blog.
Graham, as we now believe courtesy of Dirty Politics, paid Slater to run campaigns on behalf of clients. Odgers - a tax lawyer based in Hong Kong - blogged under the sobriquet Cactus Kate.
The email trail indicates that Hotchin and Kerry Finnigan were briefed on the campaign tactics.
My own inquiries indicate that Graham, Odgers and Slater believed their strategy was justified. Hotchin believed he was being vilified in the media and wanted that countered. Their posts were designed to "unspin" the viewpoints in the mainstream media. In the trio's view there was nothing illegal about that. They were simply playing hardball.
It should be noted that it is not unusual for PR merchants to wage covert campaigns when their clients are under the microscope.
When I was editing the National Business Review at the time of the Winebox Inquiry, Fay Richwhite's then PR Michelle Boag worked hard to try to undermine our disclosures.
PRs do try to get their stories into the media and will play off rival journalists if they can. The difference here is that Odgers is a lawyer.
If there was a campaign aimed at creating a climate in which potential witnesses - such as Gapes - were intimidated, that would go a lot further than simple hardball.
As Graham apparently wrote: "Our friend Tony Gapes is thinking he's a bit of a star witness for the SFO against our man. ... Trouble is it seems old Tony Gapes should have some sunlight shone on him. Enough to raise questions of credibility with the SFO."
What they were talking about appears to have gone much further than social media destruction.
Here's another thing.
Hotchin claimed when he issued defamation writs against several people, including Herald columnist Brian Gaynor and former Shareholders Association chairman Bruce Sheppard, that there appears to have been a campaign against him.
Gaynor, Sheppard and "so-called media commentators" were singled out in the email cache.
What we now know is that the hired flacks were running their own campaign.
For instance they had advised Hotchin not to speak to me.
But meanwhile they bashed mainstream media reporting of the Hanover issues at every opportunity.
Feeley maintains the SFO's investigation was not affected by the trio's apparent campaign. But Simon McArley, who ultimately announced that the SFO fraud inquiry had been closed, has reservations.
Looking through the email cache it was obvious that in some cases - notably my own writing on the FMA's inquiries - the trio subsequently formed strategies to counter the revelations.
Journalists have contacts and sources across the spectrum. Odgers and Slater were among the hundreds in my database. Odgers is well connected in New Zealand political (Act Party), business and legal circles.
In my view they - and Graham - should be called to account for their apparent actions.
The SFO has certainly been the butt of criticism before - former director Chas Sturt for his "Hollywoods" and former director David Bradshaw accused by Winston Peters in Parliament as "politically corrupt" for his failure to act on a Fay Richwhite-related matter.
As one former investigator told me yesterday: "You need balls in this job."
The fundamental point is that it's not just the SFO that needs balls, but those who bear witness.
The trio's apparent campaign was designed to stop that.
