Police arrested five members of the family of Omar al-Abed, the terrorist who murdered three civilians in Halamish (Neve Tzuf) last month.
The family members were arrested on suspicion of failing to report a crime.
The investigation into the Friday night massacre, which left Yosef Salomon, 70, his daughter Chaya, 46, and his son Elad, 35, dead, revealed that the terrorist's family knew about the attack shortly before it occurred, at the very least, and failed to report al-Abed's intentions to either Israeli or PA authorities.
Al-Abed broke into the Salomon house as they were having their Shabbat evening dinner and celebrating the birth of a new grandson.
Michal, Elad's wife, fled with their five children to the second floor, where they hid from the terrorist. A soldier, A., who lives next door, noticed the commotion and acted quickly to neutralize the terrorist. The soldier was awarded a citation for stopping the deadly attack.
The mother of the terrorist was previously arrested and charged with incitement for praising her son's murderous act.