He shortly became a member of the Moldova Swim Club under his coach Luba Pohilenco, and then officially played for the Soviet Union's senior national team before its complete extinction in 1991.

[1] Giving up his sport to support the nation's financial scarcity, Mariniuc worked as a part-time taxi driver riding around Chişinău's urban suburbs to earn sufficient rubles, Moldova's main currency, for a living.

[6] Recovering from a physical condition back in his homeland, Mariniuc pulled away from the rest of the field to claim the 800-yard freestyle title (8:19.29) at the Swim Meet of Champions in Mission Viejo, California.

[5] On that same year, Mariniuc added another coveted title in the pool to his collection at the U.S. Nationals in Austin, Texas, and later earned a silver medal for his native Moldova in the 400 m individual medley (4:11.96) at the 1993 FINA Short Course World Championships in Palma de Mallorca, Spain, finishing behind Canada's Curtis Myden by 1.56 seconds.

In 1999, Mariniuc was appointed to be the pioneer and IT director of an e-learning authoring tools company, where he programmed numerous features to implement a customer support process.

Mariniuc is currently the vice-president of a technology services company based in Sunnyvale, California, where among other support projects, he assist teams to generate and manage timing systems applied in national and worldwide swimming competitions.