A/HRC/21/50 neighbourhoods, towns and regions with civilian populations (see annex VI). The commission therefore concludes that there are reasonable grounds to believe that the war crime of attacking civilians was perpetrated in many instances. 57. There are also reasonable grounds to believe that the documented incidents constituted the crime against humanity of murder. In towns and villages where there was a pattern of blockade, shelling, ground assault and house-to-house searches, the conditions for a widespread or systematic attack against a predominately civilian population were met. The scale of the attacks, their repetitive nature, the level of excessive force consistently used, the indiscriminate nature of the shelling and the coordinated nature of the attacks led the commission to conclude that they had been conducted pursuant to State policy. 2. Anti-Government armed groups 58. Despite its limited access to victims of anti-Government armed groups, the commission was able to document cases of killing by anti-Government fighters of captured Government soldiers, Shabbiha and informers who admitted taking part in military attacks (see annex V). While the human rights legal regime differs with regard to such non-State actors as anti-Government armed groups, international humanitarian law applies equally to all parties to a conflict. 59. The commission considered corroborated evidence of killing hors de combat soldiers and Shabbiha. In Al Qusayr, Bab Amr, Qaldiya and elsewhere, the commission noted that persons captured by anti-Government armed groups on occasion faced a quasijudicial process prior to their execution. A consistent account of the trial process has not been forthcoming, nor has information on the extent of adherence to fair trial standards. Executing a prisoner without affording fundamental judicial guarantees is a war crime. 60. The commission concluded that information on executions perpetrated by antiGovernment armed groups — with or without a ―trial‖ — constituted reasonable grounds to believe that the war crimes of murder or of sentencing or execution without due process had been committed on several occasions. The commission was not able to corroborate alleged attacks directed against individual civilians not participating in hostilities or against a civilian population. 3. Unknown perpetrators 61. The commission found that scores of civilians had been killed in nine explosions between March and July by unknown perpetrators.16 The explosions appeared to have been caused by suicide bombers or by improvised explosive devices, including vehicle-borne ones. 62. While the above-mentioned acts may be linked to non-international armed conflict and thus assessed under international humanitarian law, lack of access to the crime scenes combined with an absence of information on the perpetrators hampered the commission‘s ability to make such an assessment. These are nevertheless domestic crimes prosecutable under the Syrian criminal code. The Government is obliged to ensure that an investigation is conducted impartially, promptly, effectively and independently, in accordance with its international human rights obligations. 16 See annex V, para. 55. 13