Rich cast of characters in this mystery
Jason O’Brien profiles the main players involved in the plot.
The senior Hamas commander was a shadowy figure, who lived much of his life in Syria and had survived several previous attempts on his life.
He was a founder member of the Izzedine al-Qassam Brigades and was thought to be behind the kidnap and murder of two Israeli soldiers in 1989, during the first Palestinian Intifada.
However, he left the territory to work abroad shortly afterwards. The 49-year-old was not one of the towering figures of the Hamas movement, nor was he widely known to the people of the Gaza Strip, which is ruled by Hamas.
Nevertheless, he was near the top of an Israeli hit list. It is not yet clear why he left the protection of Syria and his bodyguards to go to Dubai in the 'westernised' United Arab Emirates, although it is rumoured that he was organising an arms deal.
He was found dead in a hotel room on January 20.
Five alleged 'Irish' assassins
All five were using genuine Irish passport numbers but the documents had false names, photos and signatures.
Two of them -- Gail Folliard and Kevin Daveron -- are said to have arrived in Dubai from Paris on an Air France flight the day before the assassination took place.
A third -- Evan Dennings -- is believed to have flown into Dubai an hour later from Munich. All three left again for destinations in Europe less than 24 hours later.
The fake identities of the other two -- and their roles -- have not yet been confirmed.
Six alleged 'British' assassins
All six used real passport names and numbers, but doctored photographs and signatures.
The genuine passport holders have been traced to the Middle East. They are Melvyn Adam Mildiner; Paul John Keeley; James Leonard Clarke; Stephen Daniel Hodes; Michael Lawrence Barney and Jonathan Lewis Graham.
They all deny any involvement in the murder. Several of them have spoken of their shock at being implicated in the crime.
Mr Hodes (37) said he had not left Israel for two years and was "in shock". He said: "I don't know who's behind this. I'm scared, these are major forces."
'French' and 'German' alleged assassins
'Frenchman' Peter Elvinger was the last of the assassination team to arrive in Dubai and took a plane out of the city about an hour before the murder took place.
He is thought to be the leader of the group, but French authorities have confirmed that the passport is a forgery.
Another suspect -- this time with a German passport -- travelled under the name of Michael Bodenheimer.
A newspaper in Israel reports that a Michael Bodenheimer who moved to Israel 20 years ago has said he has no ties to Germany and that country has not yet confirmed that the passport is a fake.
Lieutenant General Dhahi Khalfan
The Dubai police commander-in chief has come to prominence in the investigation. Yesterday, he insisted that the European passports used were not fakes.
It was his decision to publish the names and passport photos of the 11 suspects.
He has also insisted that his force contacted the various countries involved at the end of January, just a week after the assassination of Mahmoud al-Mabhouh.
However, the Department of Foreign Affairs here has said it received no such contact.
Mr Khalfan indicated last night that the investigations now extended beyond the 11 individuals previously profiled to a total of 18 suspects.
Designated a terrorist organisation by Israel, the US and the EU, it is seen by its supporters as a legitimate force defending Palestinians from a brutal military occupation.
Formed in 1987, Hamas is the largest Palestinian militant Islamist organisation.
Its foremost aim is to drive Israeli forces from the occupied territories. To achieve this, it has launched attacks on Israeli troops and settlers in the Palestinian territories and against civilians in Israel itself.
It also has a longer-term aim of establishing an Islamic state.
Israel's secret service is seen as one of the most efficient intelligence agencies in the world.
It was established in 1951. Nine years later, it seized the Nazi war criminal Adolf Eichmann, who was hanged in Israel in 1962.
Its role and function in Israel are similar to those of the CIA in the US, but its director reports directly to the prime minister, Benjamin Netanyahu.