Jordanian authorities arrested a man accused of killing his 30-year-old sister on suspicion that she had a love affair, even though he had earlier signed a pledge to the police that he would not harm her, a police official said Thursday. The crime, which took place in the eastern industrial city of Zarqa on Wednesday, brings to eight the total number of women killed since January in what is known as "honor crimes." An average of 20 women are killed by male relatives each year in Jordan, a largely conservative Muslim society where men have the final say in all family matters. Many here consider sex out of wedlock an indelible stain on a family's reputation. Some women in conservative circles of the society have been killed simply for dating.