Our foray into Ireland's cold cases comes to a close this evening with a look back at the death of Kerry-born prison officer Patricia Doherty.She was reported missing on Christmas Day in 1991, after disappearing shortly after doing some Christmas shopping in the Square in Tallaght. Her body was discovered almost 6 months later by a turf cutter in the bogland of Glassamucky Brakes in the Dublin Mountains, but her killer's identity remains a mystery to this day.