Updated: 9 Jun 2021, 15:24 Invalid Date, "I JUST put the tie round his neck and just tightened it," Brian Field said of the moment he murdered a 14-year-old schoolboy in his car after raping him. "He just sort of convulsed a bit, sort of gasping for air, and I just carried on – and suddenly he went lifeless." 15 Roy Tutill was abducted, raped, and murdered as he walked home from school in 1968Credit: Enterprise News and Pictures 15 Brian Field was convicted of Tutill's murder over 30 years later - now documentary In the Footsteps of Killers asks if Field may have killed other childrenCredit: check copyright