How do you investigate Black Axe?

More than 20 years ago, BBC journalist Peter Macjob witnessed the murder of a young man by a cultist group. He has spent the last two years working with the BBC’s Africa Eye on an investigation into the group known as Black Axe. For the documentary he met face to face with members of criminal gangs. So, what does it take to carry out an investigation like this? #AfricaDaily