In November the ICC announced it would look into a possible investigation war crimes committed since 2003.
Since then it has been flooded by claims from alleged victims of airstrikes, suicide bombings, targeted killing, rape and torture.
The statements are being used by the ICC's chief prosecutor Fatou Bensouda to request an investigation be opened by the court.
Years of impunity
"I'm sure that any future case brought before the ICC would take quite some time," says Elizabeth Evanson, associate director of the international justice programme at Human Rights Watch.
"When you think about a situation like Afghanistan, you're talking about years of abuses and years of impunity."
Three judges at the ICC’s pre-trial chamber are currently considering whether to let the prosecutor launch an investigation into allegations of war crimes committed since Afghanistan ratified the Rome statute on war crimes in 2003, in the wake of the 2001 US-led invasion.
There are potentially thousands of individuals implicated in the abuse claims.
These range from organisations like Islamic State (IS) armed group to the US military and include Afghanistan's own security forces.
The ICC will not publicly comment on the case.
But in November last year Bensouda said that not only the Taliban and their allies, the Haqqani Network, were suspected of crimes against humanity and war crimes but also the Afghan security forces, the US military and the CIA.
The witness statements were collected between November 2017 and January 2018 by human rights organisations.
The ICC knows who these group are, but for security reasons, their names have not been made public.
Most victims ordinary Afghans
The victims are mostly ordinary Afghans, who have been caught up in the horror of the conflict following the 2003 US invasion.
People whose family members who were killed by gunmen, in airstrikes or simply disappeared and never seen again.
Many of the claimants only agreed to make statements once reassured that the Afghan authorities would not receive the details of the allegations, such is the fear of reprisals against them.
"In Afghanistan victims don't trust the justice system," says Abdul Wadood Pedram of the Human Rights and Eradication of Violence Organisation in Kabul. "That's why they have made their claims to the ICC."
Bensouda appears to believe there is strong enough evidence to investigate - and she hopes the judges will agree.
Specialists are more cautious, saying it is completely possible that the court will throw out the request.
If opened, the case could become one of the most complex in the court's history.