IT IS becoming increasingly clear that it is not the Iguanas incident that could kill off John Della Bosca, but a resulting cover-up.

The revelation in today's Herald that the minister wrote the apology from the Iguanas Waterfront bar to himself renders into insignificance the Premier's claim that there was no evidence that Della Bosca had acted improperly because of that apology.

Morris Iemma took the wrong course on Tuesday when he backed his embattled education minister over the incident at Iguanas, where Della Bosca and his wife, the federal MP Belinda Neal, are alleged to have threatened and abused staff.

Iemma quoted the Iguanas apology at length during the press conference, and said: "In relation to Mr Della Bosca, having examined his report, the written apology, I am not in a position to be dismissing him or standing him down."

That now looks laughable when at least two staff members stand by their statutory declarations about the night in question - which the apology was supposed to cancel out - and it turns out Della Bosca is the one who wrote the apology after at least four phone calls to the owners of the establishment.

It all would have been so much simpler if Della Bosca and Neal had just admitted on Sunday that they had behaved badly and apologised.

It all would have been simpler if Iemma had said on Tuesday that, after a series of misdemeanours, Della Bosca was on his last chance.

Instead, they've all dug in. The decision by the Della Bosca camp to get their own side to produce statutory declarations of what happened on the night now puts their own friends and allies under the microscope of a police investigation into what occurred.

Certainly, many in government are scratching their heads at the lack of credibility of a line in the statutory declaration of Neal's friend and former Labor local council candidate Kerry-Jane Stratford, who wrote: "At no time did I hear Belinda swear. I have known Belinda for quite some time and never heard her swear."