Ray Palmer, also known as his project name "Atomico", was a test subject at S.T.A.R. Labs. In the process of gaining shrinking powers, Palmer was kept in a secure container safely kept on the top floor of the building. However, two thieves named Jonathan Allen and Rhonda Pineda infiltrated S.T.A.R. Labs and, while trying to make a getaway from the cops, were hit by a lightning bolt on the roof. Pineda, although not directly struck, was sent through the floor and accidentally caused Palmer's secure container to erupt beneath her, killing the test subject inside and instead giving the thief the power to shrink. [1]

Despite his name, Atomico's powers are similar to that of Captain Atom not his mainstream counterpart.