But the head of the UN commission wants more time to complete the investigation.
Syria denies involvement in his killing, which took place after he accused Damascus of interfering in Lebanese politics.
Street protests in Lebanon in the wake of al-Hariri’s killing prompted Syria to withdraw forces that had been in the country for 22 years.
The Lebanese government and the Security Council approved plans to establish a special tribunal to try al-Hariri’s killers, but it has not yet been ratified by the Lebanese parliament.
Nabih Berri, Lebanon’s parliamentary speaker and a key member of the Hezbollah-led opposition to the current government, has not said when he will convene parliament.
Brammertz said when his inquiry was complete, it would be handed over to a prosecutor, who would finalise the investigation and prepare indictments.
He is also helping Lebanese authorities investigate 16 other politically motivated cases, including last November’s assassination of Pierre Gemayel, Lebanon’s industry minister.