The office of the prosecutor at the war crimes tribunal reached its preliminary conclusion into the killings in December 2017, submitted its findings to the Nigerian government and demanded explanations about the incident.
The ICC said the attack on IMN members, which was carried out by the Nigerian Army and condemned by human rights voices across the world, violated international statutes on human rights.
Also advancing at the ICC is its investigation into the gruesome rights abuses and killings of members of separatist Independent People of Biafra, IPOB.
The group has come under repeated assault by the Nigerian security agencies since October 2015 when its leader Nnamdi Kanu was arrested by the State Security Service in Lagos.
Mr. Kanu was later moved to Abuja where he had been standing trial until September 2017 when he disappeared following a military raid on his country home in Umuahia.
PREMIUM TIMES reported the extra-judicial killing and mass burial of over 120 people in one of several attacks on pro-Biafra supporters in May 2016 by security agencies, an incident described as “a genocide” against the Igbo by IPOB leaders.
The ICC has submitted its preliminary findings on the Shiites massacre to Attorney-General Abubakar Malami.
The ICC prosecutors said they relied on the different channels of information, including the findings of the Judicial Commission of Inquiry set up by the Kaduna State Government.
The panel had found several Nigerian Army officers culpable in the killings and recommended them for prosecution, including Niyi Oyebade, a major-general who was the Grand Officer Commanding of the Nigerian Army 1 Division at the time.
The IMN said it lost more than a thousand members in the attack that took place between December 12 and 14 at its headquarters in Zaria.
A representative of the Kaduna State Government told the commission of inquiry that 347 bodies were handed over by the army for a secret mass burial.
But despite the evidence, the army claimed it killed only seven Shiites who blocked a public road and attempted to assassinate its chief, Tukur Buratai, a lieutenant general.
It said troops only used force after it became clear that Mr. Buratai’s life was in danger.
The leader of the IMN, Ibrahim El-Zakzaky, who was arrested by soldiers during the operation, has remained in the custody of the State Security Service more than two years later — in defiance of court orders that he should be released immediately in 2016.
If the ICC chief prosecutor ultimately gives an approval for a trial to go ahead over the crimes, it would mark the first time a Nigerian would be hauled to The Hague to stand trial for crimes against humanity.
But a foreign affairs analyst, Ikenna Nwegbe, said the conclusion of investigation on the Shiites massacre might be a victory for human rights campaigners, but not likely to have any significant impact because of how Nigerian government views the allegations.
For one, Mr. Nwegbe said, the Nigerian government has failed to hold anyone responsible for either the Shiite killings or the atrocities against Igbo separatist agitators.
“Even in the case of Shiites massacre where a judicial panel indicted a major-general, the government didn’t take any action whatsoever,” Mr. Nwegbe said. “Mr. Oyebade is still in the Army till date and even flourishing.”