 He was charged on four counts of perverting the course of justice.Humble was motivated, according to Gregg after Humble's conviction, by a wish for notoriety, a hatred of the police and a fixation with the Jack the Ripper Whitechapel murders in late-19th century London.The contempt for the police dated back to 1975 when he was imprisoned for assaulting an off-duty police officer (for which he served three months in a young offenders institution), and an earlier conviction for burglary and theft in 1973.