The Real Serpent - Investigating a Serial Killer is on Channel 4 tonight at 9pm.

Part of True Crime on Channel 4. Suspected serial killer Charles Sobhraj is a free man having spent almost half his life behind bars. In this unique investigation, the notorious serial killer known as 'The Serpent' agrees to a series of psychological and criminal interrogations concerning murders that he's never been tried for, as experts try to get to the truth of the horrific crimes, bring about some accountability for the victims, and assess whether Sobhraj remains a dangerous man.

This first episode lays out the horrific crimes that Sobhraj is accused of committing in Asia. The young Sobhraj started his criminal career early in France. The film then charts Sobhraj's trail of robberies and scams in his 20s, which lead to him being imprisoned in Afghanistan.

After a shocking jailbreak, a witness describes what's believed to be his first murder. During the course of episode one, former Metropolitan Police detective Jackie Malton begins her re-examination of the murders Sobhraj is accused of, focussing on five horrific killings in Thailand in the 1970s. Meanwhile, leading forensic psychologist Paul Britton starts to explore Sobhraj's childhood and motivation. Continues tomorrow night.