From September 1974 to February 1975, Ferris was on the run. He was suspected of having taken part in a robbery at the Tralee post office, which resulted in £74,000 being stolen, and a robbery at the Chase Manhattan Bank in Shannon, County Clare in December 1974 which led to the theft of £159,000. He was arrested by Gardaí in Youghal, County Cork, on 14 February 1975, along with two other IRA members, viz., Danny O'Sullivan and Robert McNamara. The Gardaí had been on the alert after a robbery at Central Dairies in Dungarvan, County Waterford. They were later tried by the Special Criminal Court where O'Sullivan was sentenced to six and eight years concurrently. Ferris was not convicted of robbery but was remanded to Portlaoise Prison pending further charges of membership in the IRA as a proscribed organisation. He was sentenced to 12 months in Portlaoise. He was released after nine months in November 1975.