Utegate was never going to be a hit with he wider public — with a name like that how could it?

Unsurprisingly audiences dropped right off inside a week, and the show appeared to close when Parliament rose for winter recess and the principals departed for warmer climes like a flock of migratory birds.

If any memory of the event remained, it was not of a complex psychological drama, but of a kind of review skit, featuring Kevin Rudd as a ruthless political killer in the style of Josef Stalin and Genghis Khan, with his fall guy Malcolm Turnbull, a Don Quixote figure tilting impetuously at every available windmill while the Sancho Panzas who followed him watched despairingly from a safe distance. A nice night’s entertainment, but not one you’d really want to repeat.

But for the true aficionados of the political whodunit, there are still a lot of questions to be answered. There can be no doubt that Rudd emerged triumphant, and Turnbull severely damaged. This was inevitable once the widely touted email from Rudd’s adviser Andrew Charlton to Treasury officer Godwin Grech was exposed as a fake. But the question remains: who set up the caper in the first place? And almost as importantly, why? Because it must have been obvious from the start that they were never going to get away with it.

As it happened, Turnbull blew the gaffe prematurely, with is warnings to Charlton that he knew Charlton was lying to protect his boss. Given that the existence of the email had already been widely reported around Parliament House this was a clear signal that Turnbull believed either that Charlton was the originator, or at least that it had come from inside Rudd’s office. A thorough check of all the possible computers revealed that it hadn’t, which meant that Rudd was prepared to go straight on the attack.

But suppose Turnbull had kept quiet, and the story had really blown up only when Grech gave his evidence before the senate committee. With hindsight, this appears to be the way the caper was scripted, with Senator Eric Abetz apparently wheedling the admission from a reluctant and loyal public servant; yes, he could not tell a lie, he did have a recollection…

In the event, Grech, perhaps aware that things were not going strictly to plan, added that of course his memory could have been faulty, totally false even. But the revelation was certainly explosive. However, how long was it expected to stand up? Charlton would obviously have denounced the thing as a fraud, and insisted on the sweep of computers which had already been made.

Even if Rudd had had doubts about Charlton (which he didn’t) he would have called in the cops; there was simply no choice. And as soon as the cops checked Grech’s own computer they would have seen that the email certainly had been received as Grech had said, but that it had been sent not from Rudd’s office, but from inside Treasury. The fake would have been exposed; it might have taken an extra day or two, but discovery was inevitable, leaving Rudd triumphant and Turnbull and the opposition — Abetz in particular, who had lived up to his name and abetted enthusiastically — with egg all over them.

Any serious analyst would have reached this conclusion. So, again: who set it up, and why?

Some really serious conspiracy theorists within the opposition have even opined, rather desperately, that it was in fact a Labor sting; that Grech, whom they had considered a trusted informant, was in fact a double agent who had spun his fiendish web solely to entrap Turnbull. Others, more realistic believe that Grech was just a crank who was so technologically innumerate and politically illiterate that he thought the fraud would not be detected.

But if so, what was his motive? To bring down the government? And for whose benefit ? Turnbull’s? It really seems an unlikely ambition for the quivering, self-effacing mouse we saw on television. But if Grech was only a minor cog in the plot, or if he had no part in it at all and was just the sucker who received the email, then who was the mastermind?

The available evidence would seem to point to Treasury and it is here that Turnbull, Abetz and others have a problem. Of course they are perfectly entitled to protect their sources of information. All worthwhile politicians cultivate informants within the public service and while leaking is technically illegal, it has always been seen as part of the system.

But forging emails is another story: it is unequivocally criminal, and should not be tolerated by members of parliament of any persuasion. The police investigation is proceeding, and initially Turnbull promised to co-operate fully. He has since retreated from that promise and the general mood among opposition members appears to be to lay low and say nothing. In the circumstances it is probably understandable.

But if it happens that criminal charges are laid, and that Turnbull or one or more of his colleagues have been involved with the perpetrator, then the excrement will really hit the fan. Much has been written about Turnbull’s impetuosity and his tendency to overreach himself, and most of it is true. But he has another characteristic of which his supporters should beware: he does not know when to let go and there are signs that he still thinks there is some advantage to be gained by worrying away at the tattered remnants of Utegate.

Having admitted on Monday that Rudd had no case to answer, by the end of the week he had resumed the chase, accusing the Prime Minister of misrepresenting his position and demanding that he explain himself. He was loyally backed up by Joe Hockey and Tony Abbott, but the rest of his front bench was conspicuously absent. Those friends he has left should try and persuade him that it is time to cut his losses. Utegate I was bad enough; Utegate II could well be terminal.