Ferris became involved with Thompson's crime empire aged 19, when he became an enforcer, collecting debts on behalf of Thompson, and carried out stabbings, slashings, blindings and knee-cappings. A year later Ferris was arrested following an incident where shots were fired at Willie Gibson and four of his relatives while they were travelling home from a night at a pub, with Gibson's cousin John Hogg sustaining a bullet wound to his thigh. The three relatives failed to identify Ferris at an identity parade, but Gibson picked him out as the man who fired the shots. Ferris was charged with four counts of attempted murder, and was remanded to Longriggend. At his trial several months later he was acquitted on all four counts with a not proven verdict.