Dateline interviews the Australian policeman embroiled in controversy over the complex murder case of former Lebanese Prime Minister Rafic Hariri.

When former Lebanese Prime Minister Rafic Hariri was assassinated by a car bomb in Beirut in 2005, it rocked the whole of the Middle East.

He was seen as a transforming figure after years of civil war, and wasn’t scared to take on the powerful forces seeking to control his country.

But attempts to track down his killers have led investigators on a difficult and deadly journey.

Now, Dateline’s Yaara Bou Melhem has a rare interview with the top Australian policeman brought in to help solve the case.

The Deputy Commissioner of New South Wales Police, Nick Kaldas, lays the blame with Hezbollah, but attempts to try four of its members have so far failed, plunging Kaldas and the UN-backed tribunal into an international political controversy.

So what next for such a significant criminal case? And will its outcome destabilise Lebanon once again?