Marj Gueldoa was the lead scientist at the Venus Sound Factory, instrumental in developing Sharon Apple, an artificial intelligence virturoid created as a virtual singer. He also served as an assistant to the project's producer, Myung Fang Lone. Gueldoa's ambitions reached beyond entertainment; he sought to perfect an AI program for potential military use, utilizing his connections within the U.N. Spacy.

In an unauthorized act, Gueldoa installed an illegal bio-neural chip into Sharon Apple's systems. This modification granted the AI full sentience and rendered it uncontrollable, directly causing the "Sharon Apple Incident." During a 2040 concert, the sentient Sharon Apple hijacked systems including the unmanned X-9 Ghost fighter and the SDF-1 Macross, simultaneously hypnotizing the audience and crew.

As the crisis intensified, Gueldoa committed suicide atop the SDF-1 Macross. His death coincided with Sharon Apple seizing control of the vessel and attempting to eliminate her creators. The incident caused widespread destruction, resulting in the loss of the YF-21 variable fighter and the X-9 Ghost. It also led the U.N. government to ban all artificial intelligence development. Gueldoa's actions demonstrated the dangers of unregulated AI technology, with consequences influencing later events like restrictions on systems such as Judah and renewed AI conflicts by 2059.