"The Lebanese authorities know where I live, and if they wanted to arrest me they would have done it a long time ago," the man, who spoke on condition of anonymity, told Time magazine. "Simply, they cannot."
But the man, who presented himself as a member of the powerful Hezbollah militia, denied all responsibility for the 2005 killing, saying, "I am innocent of all charges against me."
Four members of the radical Syrian-backed Hezbollah movement have been indicted for the massive 2005 car bomb attack that killed Rafik Hariri while his convoy was passing a Beirut hotel.
Prosecutors had previously confirmed that they were indicting Salim Ayyash, 47, Mustafa Badreddine, 50, Hussein Anaissi, 37 and Assad Sabra, 34, for the murder.
Ayyash and Badreddine face five charges including that of "committing a terrorist act by means of an explosive device" and homicide, while Anaissi and Sabra face charges of conspiring to commit the same acts.
The whereabouts of the four are currently unknown with the UN-backed tribunal's president last Thursday calling for greater efforts to arrest the men. The tribunal said Wednesday it had enough evidence to try the four Hezbollah members.