The SSU also placed a direct presence on the estate at Cowper Downs, positioning a surveillance unit in the home of developer John Sisk, whose house backed onto Cahill's. Following the arrest of two of Cahill's associates in an attempted robbery, and resentful of the large Garda presence near his home, Cahill retaliated by ordering his men to slash the tyres of 197 cars on the night of 26 February 1988 (including 90 belonging to his neighbours in Cowper Downs).