Military records provided to ABC News show Knight joined the Navy in 2009 and reported to the Truman in 2011. He was a Machinists Mate Third Class when he left the service in May 2013, three months after investigators raided his home.
He says he was honorably discharged and “conducted [himself] professionally while on the ship.”
Knight says he’s currently employed at the technology giant Siemens as a service specialist. Siemens confirmed that Knight is employed there but declined to comment further.
Likewise, the Navy and the Department of Homeland Security did not respond to request for comment about the alleged breaches to some of their websites.
The National Geospatial-Intelligence Agency told ABC News that its “routine security measures” detected the attempted hack, and said the hack did not access employee data and “had no impact on the NGA mission.”
Attorneys for Knight and Daniel Krueger, an Illinois community college student also named in the filing, did not respond to requests for comment for this report. If convicted, the pair could face up to five years in prison or a $250,000 fine, according to the Justice Department.
The Wall Street Journal reported the allegations against Knight and his team Monday.
ABC News' Lee Ferran contributed to this report.