Across Merseyside, there is a name which has been whispered by kids for decades - "Purple Aki". Part bogeyman; part urban legend - his real name is Akinwale Arobieke. What's his story? Why has he been feared for nearly 30 years? Is he, in some senses, a victim himself? Local lad, Benjamin Zand, goes in search of the truth behind one of the UK's strangest stories.