baghdad iraq sunday execute 42 sunni muslim militants convict terrorism charge range kill members security force detonate car bomb big mass execution year iraq come sunni suicide attack kill least 60 people near southern city nassiriya shi ite area sept. 14 prompt shi ite demand tough judicial action amnesty international criticize move say monday mass execution shock display iraqi authorities resort death penalty try show respond security threats death penalty irreversible reprehensible punishment use circumstances evidence show deter crime mean punishment amnesty say report justice ministry say sunday 42 hang prison nassiriya three months 14 militants execute follow convictions terrorism islamic state claim responsibility three suicide attack target restaurants security checkpoint near nassiriya relatives victims invite witness sunday executions justice ministry say despite pain inside lose two brothers suicide attack saw terrorists dangle rope felt relief say fadhil abdul ameer nassiriya islamic state self-declared caliphate declare 2014 capture wide areas northern western iraq effectively collapse july u.s.-backed iraqi force capture mosul group de facto capital iraq recent deadly bomb attack baghdad cities show jihadists remain capable guerrilla-style warfare tactical shift away seek territorial conquest iraq hang 42 sunni militants convict terrorism