A case has been filed against unknown persons in connection with the killing of a Christian grocer, who was hacked to death in Baraigram upazila of Natore on Sunday.Victim’s daughter Swapna Gomez filed the case with Baraigram police at about 10:30pm on Sunday, said Officer-in-charge Monirul Islam.Sixty-year-old Sunil Gomez was killed when he was alone in his shop at Bonpara Christian Palli in the upazila.