Four agents from the US Federal Bureau of Investigation were at the crime scene on Friday, gathering evidence for analysis. Five French police experts, led by an agent of the anti-terrorism division, are due to arrive late Friday in Lebanon to help in the probe.

Lebanese Premier Najib Mikati emphasized the need for an investigation, "Investigation of every available [piece of] information is going on as well as we are supported by all needed expertise to divulge circumstances of this crime as quick as possible."

As the FBI investigators were combing the bomb site, Kassir's widow, Giselle Khoury, toured the site, without speaking to the agents, before going back home.

Khoury had earlier called for an international investigation, including France, to the assassination operation of the man who was described by the opposition as the "martyr of the uprising for independence."

Marwan Hamade, a previous target for assassination who had miraculously survived a car bomb in October 2004, said "Bashar al-Assad and Emile Lahoud are behind it ... Samir Kassir was a defender of democracy in the Arab world and a courageous journalist who confronted dictatorships, especially the joint dictatorship established by Lebanon and Syria."

Pictures of the FBI agents at the crime scene:

Full coverage from Ya Libnan:
* So who murdered Samir Kassir?
* Lebanon protests another murder: Pictures from Martyrs' Square
* Lebanese Journalists pay tribute to murdered colleague
* Lebanon's murdered journalist: An open letter to the Lebanese
* Vigil held to honor slain journalist in Beirut
* France & Lebanon outraged for assassination of Lebanese Journalist
* Tragedy strikes again in Beirut
* Journalist targeted and killed in Beirut explosion
* Opposition blames Lahoud and Syria for latest assassination
* Anti-Syrian journalist murdered in Beirut
* Photographs of Samir Kassir's tragic crime scene

Sources: Ya Libnan, , AP, Yahoo