For individuals it is not possible to take legal action before the International Criminal Court. It can be only filed by States, the UN Security Council or by the Prosecutor himself. It is this last option that leaves room for a role of NGOs.
Furthermore, when situations have been brought to the Court by States Parties or the Security Council, the Prosecutor can obtain information referring to crimes in the jurisdiction of the Court from other sources like physical persons or NGOs. The Prosecutor undertakes a preliminary enquiry of the said information in every case. Afterwards, if the Prosecutor decides that there are elements justifying to pursuit the enquiry, he demands at the Preliminary Chamber to authorize the enquiry.
Therefore, it is useful to transmit every substantive information on genocide, crimes against humanity and war crimes to NGOs which can communicate them to the Prosecutor.