Former Senate information technology (IT) aide Jackson Cosko was arrested for “doxxing” Republican senators during the Supreme Court confirmation hearings and threatening, “I own EVERYTHING … If you tell anyone I will leak it all.”

On Wednesday, a judge said Cosko “downloaded more information than was originally understood,” and that it was so sensitive it could not be discussed in open court.

Sen. Maggie Hassan had hired Cosko despite a prior felony conviction, then he “was asked to resign” for undisclosed, unrelated wrongdoing months before the doxxing. Rep. Sheila Jackson Lee then hired him in the House despite the felony and the prior employment trouble.

A former Senate IT aide who allegedly “doxxed” Republican senators by posting their home addresses during the confirmation hearings of Supreme Court Justice Brett Kavanaugh and blackmailed a witness “downloaded more information than was originally understood,” Judge Thomas Hogan said in District of Columbia federal court Wednesday.

Prosecutors said in November they found “terabytes of data” that they were reviewing as evidence in the case. Lawyers indicated Wednesday that what they found was so sensitive the public could not even hear it discussed. (RELATED: Republican Senators Doxxed By Someone In House Shortly After Questioning Kavanaugh)

The judge took the unusual step of kicking reporters and even Cosko’s own mother out of the courtroom for more than a half hour while prosecutors and the defense discussed what they found with the judge.

“The defense and government have filed a motion to seal the courtroom for certain matters that are not suitable for the public,” Hogan said.

After the public was allowed back in, Hogan expressed alarm.

“His accomplishments in the computer world … allowed him to do the things he was doing … there’s a sense of great risk to the public” if Cosko can access computers, he said. “If he has access to info that only he has the key to, he could cause difficulty.”

“Self-described at the time of doing it and maybe now still, he was malicious and hostile,” Hogan continued. “He downloaded more information that was originally understood. There is no combination of conditions that could ensure the safety of the community.”

Prosecutors said in court filings that even after he was caught bragging about how he used his position as a congressional IT aide to download data, and used it to blackmail an aide, he “expressed intention to commit more similar crimes while charges were pending.” (Wasserman Schultz’s Laptop Found In Phone Booth At Midnight)

Through his lawyer, Cosko, a slight 27-year-old with a buzz cut and a baggy orange prison jumpsuit, pleaded with the judge to help move him to a different jail, and said that he wanted to avoid going to trial. Prosecutors said they were discussing a plea deal.

Prosecutors also said that Cosko had a prior felony conviction — a drug charge from college. Sen. Maggie Hassan, a Democrat of New Hampshire, hired him as systems administrator and gave him access to the office’s data despite the felony record. Hassan fired him in May — or rather, he “was asked to resign” for unspecified prior misconduct, according to her spokesman. But it is not clear that she revoked his super-user IT credentials.

Then, Democratic Rep. Sheila Jackson Lee of Texas hired him — she has said in August — despite both a felony record and having just lost his job for misconduct.

After the arrest in October, the congresswoman claimed he was an intern, despite being a 27-year-old who had previously worked in the upper chamber.

A spokesman for Jackson Lee, Robin Chand, refused to tell The Daily Caller News Foundation whether the office did a background check or called Hassan’s office for a reference, and if so, what Hassan’s office said.

During the confirmation hearings of Kavanaugh, Cosko allegedly posted Republicans’ home addresses on Wikipedia, including from his computer in Jackson Lee’s office.

Then, on Oct. 2, he allegedly returned to Hassan’s office and logged into a staffer’s computer.

“The defendant was caught in the act of burglarizing the office of United States Senator Maggie Hassan (his former employer) for the purpose of illegally accessing a computer in the Senator’s office,” according to court papers. “When the defendant recognized that he was caught – by a staffer who knew the defendant well – he fled the office. However, only a few minutes later, the defendant sent a threatening e-mail to that same staffer.”

Cosko wrote, according to the papers: “I own EVERYTHING … If you tell anyone I will leak it all. Emails signal conversations gmails. Senators children’s health information and socials.”

Prosecutors said they searched his home and found “virtually a hackers’ obstruction checklist” and materials to impersonate congressmen such as stationary from Hassan’s office. (RELATED: Colleagues Fear House IT Aide Imran Awan Blackmailing Members)

Neither prosecutors nor the defense would tell TheDCNF on what legal grounds the court was barring the public from hearing the extent of Cosko’s alleged breach of Congress.

Hassan’s office has declined to answer questions from TheDCNF about what wrongdoing caused it to ask Cosko to resign in May, and why it didn’t take additional measures or even, possibly, deactivate his credentials.

Cosko previously assisted other Democratic senators including Sen. Dianne Feinstein and former Sen. Barbara Boxer, both of California, according to Fox News. Feinstein is on the Senate Select Committee on Intelligence.

Another staffer from Feinstein’s office was fired in 2013 for being a mole for China. Feinstein kept that issue quiet, and later falsely characterized that aide as a driver as opposed to a senior staffer.

One of Cosko’s lawyers claimed in October he was not an intern but a “fellow” paid for by an outside institution, according to Fox News.

But on Wednesday, a Cosko attorney told TheDCNF “there was no fellowship” and said “you’d have to take that up with Sheila Jackson Lee” as to why she called him an intern. A Department of Justice press release in October called him a “volunteer.”

Cosko comes from a wealthy California family, and his lawyer assured the judge that the family could provide him the finest mental health and drug treatment under a renowned doctor there, but the judge ordered him to be held in jail.

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