From Halopedia, the Halo wiki
Commander Jerome G. Ortega (UNSCMID 7631073) was an ONI field operative and high ranking UNSC officer. In 2511, he was put in charge of the ONI project to uncover Forerunner technology on the planet Onyx. Ortega, then a Lieutenant Commander, requested that ONI increase his funds for the project.
By 2517, however, Ortega, now a Commander, had nothing to show for his efforts. Not a single viable piece of technology had been found. Therefore, in 2525, funds were diverted from Ortega's project and then scrapped.
Ortega may have died prior to October 20, 2552, as his name appears on the ONI Memorial at ONI Alpha Site in New Mombasa. However, the memorial is not entirely reliable as it also mentions Margaret Parangosky, who is known to have been alive at the time, along with every ONI member named at the time of the release of Halo 3: ODST.
List of appearances