Maruru became one of the top commanders of the Kikosi Maalum, a contingent of troops commanded by Tito Okello and Oyite Ojok. In 1979 during the Uganda National Liberation Front (UNLF) Government, Maruru became a member of the "National Consultative Council", which was the Parliament at that time. After the fall of President Godfrey Binaisa in 1980, the Uganda National Liberation Army (UNLA) appointed Maruru to the Military Commission to run the affairs of the country. General elections were held in Uganda in 1980 and Maruru was appointed Brigade Commander in Northern Uganda based at Gulu. He was later transferred to command the Brigade in Western Uganda. He was appointed as Chief of Operations and Training in the UNLA. When Tito Okello and Bazilio Olara Okello overthrew Obote in 1985, Maruru was promoted to the rank of Brigadier and shortly after to Major General. He was then appointed UNLA Chief of Staff. When the National Resistance Army (NRA) rebels overran Kampala in January 1986, Maruru was among the high-ranking officers who surrendered there. He personally met NRA leader Yoweri Museveni at Kampala's Republic House, telling him that he was content to be treated as prisoner of war or be released. To his surprise, Museveni offered him a job in the NRA. Maruru accepted, and went on to serve in Uganda's new national army. In 1990, he was appointed as General Manager of Uganda Air Cargo. Maruru retired in 2002. In his later life Maruru suffered from hypertension. He died on 11 January 2014 at Mulago Hospital in Kampala.