Syrian human rights groups have called for an investigation into the suspected murder of Hiba Suhaib Haj Aref, a Syrian activist who was found hanged at her house in Bza’a city, Aleppo province, on Tuesday. Hiba Suhaib Haj Aref, referred to by many as “Hiba Haj”, had received multiple death threats in the preceding weeks, the Syrian Network for Human Rights (SNHR) reported. According to SNHR, the police has launched an investigation into her death, but the network regretted that local authorities did not investigate the death threats she received when still alive. “We call on the Syrian Interi…