BEIRUT: Investigators have pored over evidence for four years — a human tooth found at the bombing site, a suicide truck that was stolen in Japan and made its way to Lebanon, reams of phone records and hundreds of interviews.

Now the focus in one of the Middle East’s most dramatic political assassinations is shifting to prosecution, with the convening today of an international tribunal on the slaying of former Lebanese Prime Minister Rafik Hariri.

Despite the start of proceedings in the Netherlands, it is still not known who will be accused in the suicide truck bombing that killed Hariri and 22 other people on a seaside street in Beirut on Feb. 14, 2005.

Also unknown is the most politically explosive question — whether the proceedings will implicate Syria’s government, which many Lebanese believe was behind the murder of a man who led opposition to the long Syrian military occupation of Lebanon. Syria has denied any involvement.

Most likely the first defendants before the court will be four pro-Syria generals who led Lebanon’s police, intelligence service and an elite army unit at the time of the assassination. They are the only people in custody, though they have not been formally charged.

Some in Lebanon doubt the court will ever bring out the full truth, believing it might avoid digging deep to ensure political stability. Trials could also further polarize Lebanon’s politics, feeding the power struggle between pro- and anti-Syria factions. The UN Security Council had to impose the mixed Lebanese-international Special Tribunal after Lebanon’s Parliament was too divided to approve it. Administrators have said the tribunal will take up to five years to finish its work, and the top UN prosecutor, Daniel Bellemare of Canada, said in a statement yesterday that it will be thorough.

“We will not be deterred by the obstacles or the size of the challenges,” Bellemare said. “We will go wherever the evidence leads us. We will leave no stone unturned.” As prime minister, Hariri was credited with rebuilding downtown Beirut after the 1975-90 civil war.

In a country known for political assassinations, his killing stands out for its far-reaching impact. It galvanized opposition to Syria and helped force the end of a 29-year military presence that dominated Lebanese affairs.

The first UN investigator into the killing, Detlev Mehlis of Germany, said the assassination plot’s complexity suggested a role by the Syrian intelligence services and its pro-Syria Lebanese counterpart. Lebanon’s pro-US government detained the four generals. But the two chief investigators who followed Mehlis have worked quietly and have not named any individuals or countries as suspects. Last April, Bellemare said investigators had evidence Hariri’s killing was done by a “criminal network.”