Donald Macintyre: A murder mystery no nearer solution

The puzzle seems to get more baffling each day. With another 15 suspects named by Dubai police in connection with the extrajudicial killing of Mahmoud al-Mabhouh, the conclusion to a saga which would strain the credulity of even an avid spy novel reader seems no closer.

Israel is still refusing to confirm or deny its involvement in the assassination, while yesterday the dead man was reported from Gaza to have himself been a master of disguise.

At least eight of those on this week's new list of suspects – the latest in a carefully managed and progressively released series of announcements from the Dubai police – used passports bearing the names of people living in Israel. And of the eight, all those contacted by journalists – like the six British-Israeli dual nationals whose names were used by the first batch of 11 suspects – have said their identities were used without their permission.

One of the strongest reactions so far from any government, and one of the most explicit in hinting that Israel was likeliest to have been behind the operation, came from Australia, three of whose citizens appeared on the latest list.

Foreign Minister Stephen Smith said that if Israel was behind the killing, Australia "would not regard that as the act of a friend". The Prime Minister, Kevin Rudd, added that Australia would "not remain silent" on the issue and that any state "complicit in the use and abuse of the Australian passport system, let alone for the conduct of an assassination is treating Australia with contempt."

From Israel itself, there have been varying signals. Opposition leader Tzipi Livni has said the killing was "good news to those fighting terrorism", while The Washington Post quoted an unnamed Israeli official suggesting that allies in the US and Europe who co-ordinated the "war on terror" with Israel were less exercised than their public statements implied.

But one newspaper specialist in intelligence, Yossi Melman in Haaretz, said the evidence against Israel remained "weak" and questioned whether 26 agents would have been deployed to kill a single Hamas militant by the methods attributed to them. He pointed to reports from Dubai that two of the hit squad had fled by boat to Iran, an unlikely refuge for the Israeli spy agency Mossad.

Meanwhile Reuters has quoted a "confidant" of Mr Mabhouh, as saying that he too used fraudulent passports and disguises while acting as an arms supplier to Hamas.

"He used to wear coloured contact lenses and dye his hair when travelling to European countries," the unnamed associate said.

"He had many passports of different nationalities – all Arab," he added. "Recently he underwent surgery to reshape his nose. It became narrower."

But in possible conflict with suggestions that the man was importing arms from Iran, the man said Mr Mabhouh had not visited the Islamic Republic in the past three years.

He added that the Hamas militant took personal security very seriously, from wrongly shooting at a Syrian car that drove repeatedly past his home in Damascus – it was in fact carrying "minders" – to shunning room service in hotels.

The answer to the question of how exactly that security was breached in Dubai is one of many yet to emerge.