Hamas activist Mahmoud al-Mabhouh was murdered by assassins in Dubai. But what was he doing there?
Why was Mahmoud al-Mabhouh in Dubai? That central question about the senior Hamas figure murdered in his hotel room last month remains unanswered despite the reams of speculation about the hit squad which carried out the operation and left behind a lot of evidence on CCTV.
Hamas have refused to comment on the reasons for Mabhouh's trip and have limited their responses to promises of revenge against Israel.
Israeli officials have accused Mabhouh of helping smuggle rockets into the Gaza Strip, the coastal territory ruled by the militant group.
A Hamas statement last month acknowledged Mabhouh was involved in the kidnapping and killing of two Israeli soldiers in 1989 and said he was still playing a "continuous role in supporting his brothers in the resistance inside the occupied homeland" at the time of his death.
Hamas figures denied reports that he was en route to Iran, a major Hamas backer. But the group has not given clear reasons for his presence in Dubai.
So who was Mahmoud al-Mabhouh?
The 50-year-old was a senior military commander in Hamas, the Palestinian Islamist organisation.
Born in the Jabalya refugee camp, one of 14 children, Mabhouh was a secondary school drop-out who was apprenticed as a car mechanic and eventually opened a garage.
He was a keen body-builder in his youth and won a weight-lifting competition.
After joining the Muslim Brotherhood in 1978, he met Sheikh Ahmed Yassin, who went on to become the founder and Gaza leader of Hamas before being assassinated by an Israeli strike in 2004.
Mahmoud had been among Brotherhood groups questioning the-then relatively peaceful role of the movement.
He joined its first underground cell and after being imprisoned for possession of an AK-47, he became a founder member of Hamas in the year the first Intifada erupted in his own neighbourhood of Jabalya in 1987.
He was married with four children.
According to his niece, Hiba, an attempt was made to capture Mabhouh in Beirut in 1999. His Egyptian and Sudanese would-be captors had intended spiriting him away by boat, but he escaped.
She described the assassination of her uncle as a "Hollywood production but it didn't have the happy end of a Hollywood movie".
She said the international row over the operation was "a big blow to Mossad. This is not the end they wanted."
Yaakov Katz in The Jerusalem Post identified Mabhouh as a key link in the smuggling of weapons into Gaza via Sudan, and suggested that his death is a serious blow to the operational capabilities of Hamas.
According to some reports, Mabhouh was the target of an assassination attempt three months ago that left him in a coma for more than day.
If true, this makes it all the more surprising that a known militant leader - said to be on an Israeli hit list - would leave the security of Syria and travel without bodyguards to Dubai.
What was he doing in Dubai?
There are two conflicting explanations - one involving a planned arms deal, the other a conspiracy.
Mabhouh was widely believed to be a player in the murky and dangerous world of weapons dealing - where deals can sometimes go badly or lethally wrong.
Regarding the arms deal scenario, Mabhouh's fate was sealed when Israeli intelligence learned about a weapons purchase set to go ahead in Dubai.
A Mossad hit team was scrambled and killed the top Hamas figure before he could arrange to buy arms to target Israel.
Israel's Ynet News reported that Mabhouh was "on a mission" when he was killed.
The newspaper Haaretz said Dubai was known to be a place where "anyone can bank".
"Half the money al Qaeda spent on 9/11 attacks was sent to the perpetrators in the United States through Dubai banks," the newspaper reported.
Haaretz reported that Dubai is a vital centre in Iranian sanction-busting, with a projected $15 billion (NZ$21.5 billion) of trade between Iran and Dubai.
Commentator Zvi Barel wrote: "Were the arms deals that Mr Mabhouh reportedly did with Iran part of this vast trade? There is no reason to think differently."
The alternative reason for Mabhouh's presence in Dubai has do with bitter Palestinian rivalries, and raises the prospect that he was led to his death by trusted lieutenants.
The Jerusalem Post reported suspicions that the Palestinian Authority, run by Hamas's rival organisation Fatah, might have had a hand in the attack.
This week the Guardian reported that a third Palestinian, this time a Hamas official, was being interrogated by Syria in connection with the operation.
Dubai police have cited telephone records in suggesting the hit team was based in Austria, but scrambled to reach Dubai before Mabhouh arrived.
They apparently had enough time to plan and execute a complex operation involving as many as 17 operatives, disguises and radio communications, as reported in the media.
Somehow his killers knew all about his itinerary and the fact that his usual posse of bodyguards were not around - raising the possibility that Mabhouh was handed on a plate to his assassins by people he felt he could trust.
According to the Dubai police he was travelling under an alias - Mahmoud Abdul Raouf Mohammed.
But Ynet News reported a Hamas spokesman, Talal Nasser in Damascus, as saying that Mabhouh had travelled to Dubai in the past without using a different name.
Ynet said he had five identities which he could have used, but did not.
Mabhouh flew to Dubai without his usual security team, and was relaxed enough about the trip to continue with his plans when his bodyguards couldn't get tickets on the same plane.
"He would take his bodyguards with him wherever he went, but there was no room for them on the flight," Nasser was reported as saying.
The bodyguards had to buy tickets to join him the next day, Ynet News reported. Dubai police have reported that the aircraft and hotel booking were made only a day before travel.
Two Palestinians who tried to flee the United Arab Emirates to Jordan last week were arrested and are being interrogated by the Dubai police.
At least one of these Palestinians is said to have had contact with the hit team before Mabhouh was murdered.
So who was behind the killing?
Most speculation centres on Mossad, even though aspects of the tradecraft at work appear brazen rather than discreet - for instance the donning of fake beards and glasses in view of security cameras.
Moreover the killers used the names of Israeli citizens for fake passports.
It is possible that the job was a false flag operation - where a foreign agency killed Mabhouh but made it look like a Mossad killing.
A former high-ranking Mossad official, Rami Igra, told Israel Army Radio that the assassination "does look professional".
Igra added that it "doesn't look like an Israeli operation" because of the apparent shortcuts, such as allowing members to be videotaped by security cameras.
Any number of governments had a price on Mabhouh's head.
For instance Fatah, Hamas' rival for control of Palestine, has links with several Middle Eastern and European intelligence agencies.
Egypt, Saudi Arabia and Turkey have differences with Hamas; even Iran has had rifts with Hamas members in the past and a track record of foreign assassinations.
And there are the two Palestinians being investigated in Dubai for the killing.
Hamas leaders identified the suspects as members of security forces loyal to the Fatah movement of Palestinian President Mahmoud Abbas, implying but not explicitly saying that Fatah collaborated with Israel in carrying out the killing.
They named the two as Ahmed Hasanein and Anwar Shehaybar.
Responding to the Hamas allegations, Palestinian Authority spokesman Ghassan Khatib said: "We're confident the PA was not involved."