Palestinians in the Gaza Strip are used to violence, but not the brutal murder of a foreign sympathizer shown blindfolded in the hours before his execution. Hamas, which runs the enclave, espouses an agenda focused on the Palestinian nationalist conflict with Israel. So, unlike the militants in Iraq and Afghanistan who have kidnapped and killed Westerners, Hamas's leadership has sought to build support and sympathy for its cause in the West. A British journalist kidnapped by a fringe militant group in Gaza four years ago was released unharmed days after Hamas won a brief civil war and took control. An Israeli soldier captured by Hamas and its Palestinian allies during a border raid in 2006 is still believed to be alive in captivity. There is genuine outrage in Gaza over the cold-blooded killing of Vittorio Arrigoni, an Italian activist who lived in the enclave for two years helping Gaza fishermen deal with Israel's tight maritime blockade. “I was about to cry when I heard the news. That man quit his family for us, for Gaza, and now Gazans killed him. That was so bad,” said supermarket owner Abu Ahmed. Samira Ali, a teacher, said: “Those who killed him are not Muslims and certainly not Palestinians.” Hamas spokesman Fawzi Barhoum denounced the crime as an attempt “to harm international solidarity with besieged Gaza and to damage the image of the Palestinian people”. But there was also a shiver of fear that extremists who want Gaza to be a militant theocracy are bold enough to challenge Hamas over what they consider its lack of religious fervor. Friends and fellow pro-Palestinian activists said Arrigoni, a blogger, was well known in Gaza and well liked. His captors, calling themselves Jihadist Salafi, saw him as an infidel who “entered our land only to spread corruption”. They seized the 36-year-old to force Hamas to release their leader, Hesham Al-Sa'eedni, who was arrested last month and identified by Gaza sources as an Egyptian senior member of the Tawheed and Jihad group linked to Al-Qaeda. This group denied responsibility, but observers said the message of the kidnappers bore all the hallmarks of the Jihadist Salafi and could be an autonomous cell of this movement. “They knew Hamas was not going to agree to their demands and so they killed him in order to send a message,” said political analyst Hani Habib. “It is a sign of doubts over the security situation in Gaza and whether it is stable as Hamas says.” Hamas security forces arrested two men and were seeking others suspected of involvement, as senior figures in the movement scrambled to condemn an “ugly crime” totally alien to their beliefs and insist that Hamas's grip remains intact. Hamas, which has run the enclave since 2007, said Arrigoni's abductors “had the intention to kill the Italian from the beginning, and the proof was that they had killed him hours after the announcement of their demands”. Interrogation of one of the group disclosed the location where he was being held, but he was already dead. Habib believes radical splinter groups ready to defy Hamas are now competing to demonstrate who is the more extreme. Hamas itself is an Islamist political movement which places religion at the center of its mission to end Israeli occupation of Palestinian land. Hamas was founded in 1987 as an offshoot of the Egyptian Muslim Brotherhood. An Israeli security official, who did not wish to be named, said: “We've been watching these kind of challenges to Hamas for a while. The obvious relevance to us is the question of whether Hamas is still in charge.” But for Israel, Hamas was still answerable for any violence from Gaza, and recent fighting in which at least 36 Palestinians were killed in Israeli strikes in response to rocket fire “made clear that it was in Hamas's interest to assert order”. There are half a dozen radical groups in Gaza with membership numbering in the hundreds. The differences between them are unclear. Some analysts believe they work in cells to evade Hamas pressure. All want to end Western influence and establish an Islamic state across the Middle East. Hamas wants a Palestinian state, albeit an Islamic one. It has largely refrained from imposing Islamic law since taking control of Gaza in 2007 and has also condemned Al-Qaeda attacks in Western cities. Hamas, with some 25,000 men under arms, has said its more radical rivals are simply misguided offered them “reeducation”.