If you watched The Serpent, there is a chance you were left traumatised by the crimes of Charles Sobhraj. The con artist and serial killer robbed tourists by making them sick and dependent on him. 

But how did he exactly do this?

Charles narrated and even boasted of his crimes to Richard Neville and Julie Clarke for their book ‘The Life and Crimes of Charles Sobhraj'. Of course, he later denied them and even said that he never confessed to the killings in Thailand, Nepal, Malaysia, India and Pakistan. However, in this process, the writers did manage to get their hands on some useful information about how he made his victims powerless. 

Source: New Indian Express

He gave his victims drugs to render them helpless. 

Marie-Andrée Leclerc, Charles' accomplice and lover gave a testimony in the summer of 1976 in New Delhi, saying that Charles' favourite method to subdue his victims was by making them ill. He would use anything could get his hands on. This ranged from diarrhoea inducing medicines to itching powder to render the people who stayed with him weak and reliant on him. 

In some cases, Charles also used fast-affecting drugs on his victims to bring on a downer before robbing them. Post which, he often strangled, shot, or mutilated them before burning their remains, in order to avoid quick and easy identification.

What were the drugs he used?

In specific cases in Bangkok, Thailand, like he did with Dominique, Charles would invite travellers to stay with him. Especially when he wanted someone to work for him for long periods, he poisoned them under the ploy of providing them dysentery medication. If you've seen the show then you know exactly what I'm talking about. 

Source: TheSun / AFP

According to the statements, Charles bought Kaopectate powder, an antacid medication used to treat temporary discomforts of the stomach, used commonly in Thailand. And mixed it with Mogadon, a hypnotic drug used for short-term relief from severe, disabling anxiety, and insomnia. By giving this to his victims, under the pretext of helping them, Charles made sure that they were no longer able  to function on their own. 

Source: Rex Features / GQ

He also used Mogadon pills, used to treat insomnia. And other drugs like Largactil, which is highly sedative and used to treat severe depression, behavioural disturbances, nausea, vomiting, severe pain and unstoppable hiccups. He also used an illegal drug called quaaludes, which is a sedative with hypnotic properties. 

Source: Distractify

He tried everything in the book to make sure his victims had no self-control left. He is believed to have murdered 24 people and robbed many more than we know of.