The Israel Security Agency (ISA, also known as the Shabak or Shin Bet) has arrested Wissam Hussein Dawabshe, whose sister Riham was killed in the Duma arson attack. He is suspected of security offenses, which some reports say include membership in Hamas.
No further information has been released about Wissam.
Riham Dawabshe, her husband Saad, and their 18-month-old son Ali were all killed after their home was firebombed last summer. Only the elder son, who was four years old at the time, survived.
Israeli security forces quickly began cracking down on Jewish extremists. A number of people were arrested and two were charged with perpetrating the attack.