He is the mysterious figure looming large over the world's biggest crime scene, decked out in a blue business shirt and bulletproof vest.

In the days since MH17 was struck by a surface-to-air missile and crashed in Ukraine, his face has been splashed across newspapers and television screens. In the absence of a force of international investigators, he has become the world's eyes and ears at the site of the wreckage.

Alexander Hug visits the crash site in Ukraine. Credit:AFP

But who is Alexander Hug and who is behind a determined campaign to keep him from discovering the truth?

On scene hours after the crash, the hulking examiner is no stranger to war. The lawyer-turned Swiss Army soldier has built a career out of trying to keep the peace in some of the world's biggest hotspots. He's been on the ground in Kosovo, Hebron and at one stage, served as a commander in war-torn Bosnia. In April, he was appointed the deputy chief monitor in Ukraine for the Organisation for Security and Co-Operation in Europe (OSCE).