The current official website of International Criminal Court (ICC) has comprehensive research resources including basic legal texts relevant to doing research relating to ICC. The Official Journal includes the full text of the Rome Statute, the Rules of Procedure and Evidence, and Regulations of the Court. Key filings, transcripts as well as decisions can also be searched by party names and docket here. The UN Secretariat ceased to serve as the ICC Secretariat in 2003 when the Permanent Secretariat of the assembly of State Parties to the Rome Statute was established but the pre-2003 website of the Court contains documents on the drafting history of the Rome Statute and notes from the Preparatory Commission.
The website ICL Database and Commentary provides a basic research tool which links international criminal law cases with its corresponding legal texts in the Rome Statute and commentary. More treatises and commentaries can be found in L1 of the Law Library with the call number KZ6310. In Morris, one can locate these titles by doing an advanced search by subject heading phrase "International Criminal Court" combined with word in the subject "History" for its drafting history and combined with word in the subject "Rules and Practice" for procedural materials.
Other relevant secondary sources include reports from NGOs such as the War Crimes Research Office, International Bar Association's IBA/ICC Monitoring Report, Victims Rights Working Group.