14:43, 6 JUN 2016 UPDATED 15:32, 6 JUN 2016 BY STEVE ROBSON , LAURA ELVIN David McGreavy, now 65, murdered Paul, Dawn and Samantha Ralph in 1973 in one of the most shocking crimes in British criminal history David McGreavy was pictured out on day release from prison in 2006 One of Britain's most…