But despite months of investigation, prosecutors had been unable to bring charges against the 29-year-old man, who was identified on Tuesday as a former CIA employee being held in a Manhattan jail on unrelated charges, the Washington Post reported.
Joshua Adam Schulte, who worked in the CIA's Engineering Development Group tasked with designing computer codes to spy on foreign adversaries, was behind the "Vault 7" leaks of top-secret CIA information, the daily said.
He is believed to have provided the confidential data to WikiLeaks.
According to the Post, federal prosecutors obtained a search warrant in 2017 for personal computers and hand-written notes from his apartment, but no evidence linking Schulte to the disclosure was found.
A government prosecutor disagreed with what he called the "characterisation" by Schulte's attorney that "those search warrants haven't yielded anything that is consistent with (Schulte's) involvement in that disclosure".
But the prosecutor, Matthew Laroche, an assistant US attorney in New York, said that the government has not brought an indictment, and that the investigation "is ongoing" and Schulte "remains a target of that investigation," according to a court transcript of the January 8 hearing that escaped public notice at the time.
Part of that investigation, Laroche said, was analysing whether a technology known as Tor, which allows Internet users to hide their location, "was used in transmitting classified information".
Schulte said in a statement to the Post that he was innocent, arguing that the CIA targeted him because he was the only member of his team to leave the agency after reporting "incompetent management" to its inspector general.
"Due to these unfortunate coincidences the FBI ultimately made the snap judgment that I was guilty of the leaks and targeted me," Schulte said.
He is currently in custody for "possessing, receiving and transporting child pornography", according to an indictment lodged in September. He has pleaded not guilty.
According to certain current and former intelligence officials the Vault 7 disclosures could cause more damage than those done by former National Security Agency contractor Edward Snowden.
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