A subsidiary to the Special Forces, the Outerworld Investigation Agency was formed by Sonya Blade and Jax after Shao Kahn's invasion of Earthrealm. Through technology, the OIA was able to develop effective inter-realm portals that allowed them to traverse the realms with relative ease. The agency's main goal was to destroy any ancient portals that still existed between Earth and any other realms. Thus destroying any remaining threats to Earthrealm by outside forces.

During the events of Mortal Kombat: Deadly Alliance, the Red Dragon, considering the OIA a threat, sent Hsu Hao to infiltrate the OIA headquarters and plant a bomb. The resulting explosion disabled the OIA's abilities to travel between realms. Special OIA agent Cyrax was now trapped in Outworld. However, with the help Nitara, he was able to return to Earthrealm.

The current status of the OIA is unknown, at this time.