Was it the minister in the hospitality box with the cigar, the minister with the politically incorrect joke book or the minister with the entire Defence Force at his disposal?
Or, as they would have it, was it none of the above?
A report in Australian media that a Kiwi minister booed and bad-mouthed the Wallabies while hosting the Australian Rugby Union during the Italy match at North Harbour on Sunday sparked an intriguing game of Cluedo in Parliament.
It also sparked a string of outright denials from the three ministers who were in the hospitality box, Wayne Mapp, Maurice Williamson and Jonathan Coleman.
The report in the Sydney Morning Herald said the "Minister of Bad Manners" called the Wallabies' f****** cheats' and booed before leaving when Australia began to assert dominance. An official had told one offended Australian that he could do nothing because it was a government minister.
The Australian Rugby Union - some of whom were sitting behind the ministers - refused to confirm or deny it yesterday, which did little to dampen the speculation.
Labour leader Phil Goff said if it was true, it was potentially a sackable offence.
"It's one thing to tease the Aussies, we do that all the time and they do it back to us, but if you're hosting a country in your own country it's certainly not appropriate to be abusive."
The day began with multiple suspects. Male, female, good or naughty, few were spared the interrogation. One by one they provided alibis.
It soon emerged the three ministers charged with hosting the Australians that night were Dr Mapp, Dr Williamson and Dr Coleman.
Williamson and Coleman had prior form - Maurice Williamson enjoys the occasional off-colour joke and others who shared a box with him in the past said he was a vocal spectator.
Jonathan Coleman had the corporate box run at a U2 concert in 2006, involving a cigar (his), a water pistol (the woman who took offence at his cigar) and a punch.
They presented denials in unison. There was no booing, swearing or sledging in their box, they said. They had all enjoyed the game immensely.
They stayed on for half an hour after the game, none had done anything nor seen anything untoward.
"It is an unnamed source talking about an unnamed minister," Mr Williamson said. "All I can be is accountable for my own behaviour and absolutely nothing wrong was done or witnessed."
The upstairs referee - Prime Minister John Key - listened to their version and then rang two independent witnesses to corroborate it. He undertook a forensic analysis. The clincher was that the minister in question had reportedly left the box in a huff when Australia began to assert dominance.
"That was in the early part of the second half. In fact, all three ministers have assured me they ... stayed for the entire game."
The least likely suspect of the three - Dr Mapp - had his own theory.
"The writer got it wrong." he said. "I think this is essentially a made-up story. There is nothing to see here."
As one observer pointed out, someone was lying and it was either an Australian or a politician.