An investigative report by the Canadian television station CBC has unequivocally concluded that Hezbollah was involved in the 2005 murder of former Lebanese Prime Minister Rafik Hariri. The report also named one of the suspects fingered by the UN commission investigating the murder: Wissam Hassan, today Lebanon's intelligence chief, who at the time was Hariri's chief of protocol.

Documents obtained by CBC indicate that Hassan has very close ties with senior Hezbollah officials, including Hussein Khalil, one of Hezbollah secretary general Hassan Nasrallah's top aides.

The report said the UN probe had evidence pointing to Hezbollah's involvement as early as 2006, but initially failed to pursue it. This evidence was supplied by a Lebanese police officer, Capt. Wissam Eid, who was himself assassinated in 2008.

Only in October 2007 did the commission finally order an analysis of Lebanese phone records. Two months later, this analysis produced a list of mobile phone numbers belonging to people apparently involved in the attack, including eight who, based on their cell phone data, had evidently been shadowing Hariri in the weeks before his death.

But it turned out Eid had supplied these same numbers, based on the same analysis, in early 2006 - but was ignored.

These eight phones, dubbed the "red phones," were used only to communicate with each other before the murder, and were never used again after it. But the analysis revealed that each of these eight people also used a second phone to communicate with a larger network, dubbed the "blue group."

Eid had been monitoring the blue group's calls, but his break came when Hezbollah shut down the network and collected the phones. Some of the phones still had time remaining on them, and the man Hezbollah assigned to collect them, a junior electronics specialist named Abd al Majid al Ghamloush, used one to call his girlfriend. That enabled Eid to put a name to him.

Like the red group, blue group members each had a second phone, and Eid also tracked these. His phone monitoring eventually led him to two Hezbollah operatives, brothers Hussein and Mouin Khreis, one of whom had been on the spot when Hariri was killed. It also led him to the "yellow group," which was apparently a longer-term surveillance team.

Finally, he discovered that all the phones he was tracking were linked in some way to landlines at Hezbollah's Great Prophet Hospital, located in a Hezbollah-controlled section of Beirut. Hezbollah has long been thought to have a command center in this hospital.

Later still, the probe discovered the "pink group" - four phones that had communicated both with the hospital and, indirectly, the other networks. All four had been issued by the Lebanese government, of which Hezbollah was part in 2005. The UN commission asked the Lebanese Communications Ministry who owned them, and CBC obtained a copy of the response: Beside each phone number was the word "Hezbollah."

At one point, Eid himself was warned off by Hezbollah. Then, to underscore the message, someone tried to kill his boss, Lt. Col. Samer Shehadeh. Shehadeh survived the September 2006 bombing attack but was severely injured.

In January 2008 - a month after the UN probe had first reproduced Eid's findings and then rediscovered his lost report - it sent its telecommunications experts to talk with him. But on January 25, 2008, the day after their second meeting, Eid was assassinated in a bombing attack identical to the one that killed Hariri. Apparently, Hezbollah had found out about the meetings.

One person the phone records cast particular suspicion on was Hassan, Hariri's former chief of protocol. He was not with Hariri when the assassination occurred, and had told UN investigators this was because he had a university exam later that day and spent the entire morning studying - with his cell phone off.

That alibi made UN investigators suspicious even at the time. But Serge Brammertz, then head of the commission, refused to allow them to investigate further, for political reasons.

The phone records, however, showed that Hassan had in fact made 24 calls that morning, an average of one every nine minutes. They also showed that from late 2004 to the end of 2005, he spoke with Khalil by phone 279 times. During that same period, Khalil had 602 phone conversations with Wafa Safik, head of Hezbollah's internal security department.

Moreover, Hassan became head of ISF - the Lebanese security service for which Eid also worked - after the assassination, and would thus have known about his January 2008 meetings with the UN experts.

But despite all the telecommunications evidence obtained by both Eid and the UN, one problem remains: It is not evidence that would stand up in a court of law. Whether the commission will ever succeed in collecting the necessary supporting evidence remains unknown.