A former IT aide to New Hampshire Democratic Sen. Maggie Hassan mounted an “extraordinarily extensive data-theft scheme” against the office, the culprit’s plea agreement states.

The plot included the installation of tiny “keylogging” devices that picked up every keystroke. Between July and October 2018, former IT aide Jackson Cosko worked with an unnamed accomplice, a then-current Hassan employee, who repeatedly lent him a key that he used to enter the office at night and who allegedly tried to destroy evidence for him.

Cosko accepted responsibility for the events revealed by federal prosecutors in court Friday.

A statement of facts that Cosko agreed to says that from July to October 2018, he “engaged in an extraordinarily extensive data-theft scheme, copying entire network drives, sorting and organizing sensitive data, and exploring ways to use that data to his benefit,” arranging it into folders such as “high value.”

The theft occurred after Cosko was fired from Hassan’s office in May 2018 for undisclosed reasons, then hired by Democratic Texas Rep. Sheila Jackson Lee, giving him access to the House computer network. (RELATED: Suspect In Kavanaugh Doxxing Downloaded ‘More Information Than Originally Understood)

“The defendant gained access to Senator Hassan’s Office by unlawfully obtaining keys from a staffer who was (at the time) still employed in the Office” and using it to repeatedly burglarize the office. He placed small, unobtrusive devices on at least six Senate computers that captured every keystroke, including usernames and passwords which he would then use to access further documents.

He repeatedly sneaked into her office late at night and gathered dozens of gigabytes of data including:

dozens of usernames and passwords belonging to Senate employees

tens of thousands of emails and internal documents

credit card information belonging to Senate employees

social security numbers belonging to Senate employees

personally identifying information belonging to hundreds of other persons (presumably constituents)

private phone numbers and home addresses of senators

In October 2018, he used information stolen from Hassan’s office to doxx Republican Utah Sens. Orrin Hatch and Mike Lee as well as Republican South Carolina Sen. Lindsey Graham. Republican Kentucky Sen. Rand Paul later called for punishing the then-unknown offender. Cosko then doxxed Paul and Senate Majority Leader Mitch McConnell. “The defendant published that information maliciously, with the intent to intimidate the Senators,” the plea agreement says.

On October 2, Cosko again borrowed a key from the accomplice who knew “that the defendant intended to unlawfully enter the Senator’s Office that night.” At 10p.m., went back to Hassan’s office for more data, but was caught in the act by another Hassan staffer, who he then threatened: “If you tell anyone I will leak it all. Emails, signal conversations, gmails,” he said. (RELATED: Hearing Reveals Congress Provided ‘No Supervision’ Of IT Aides, Missed Red Flags, But Members Block Proposed Reforms)

The next day, Cosko met with his accomplice, referred to as Subject A, and returned his key and “told Subject A to wipe down all of the computers, keyboards and computer mice.” But a third witness nearly caught him in the act, so the accomplice texted Cosko: “Hey So I was able to wipe down the keys and mouse but [witness 3] was coming so I could [not] do the other thing.”

Cosko pleaded guilty to five felonies including witness intimidation and obstruction of justice. The maximum sentence was 55 years in prison, but guidelines call for three to four years. He agreed not to seek a term shorter than two years as part of the plea agreement. He could also face a fine of up to $200,000 and possible restitution to Hassan’s office.

Prosecutors declined to say whether the accomplice will be prosecuted, and Hassan’s office did not return a request for comment.

The plea agreement says that from July to October 2018, Cosko:

engaged in an extensive computer fraud and data theft scheme that he carried out by repeatedly burglarizing Senator Hasson’s office. The defendant engaged in an extraordinarily extensive data-theft scheme, copying entire network drives, sorting and organizing sensitive data, and exploring ways to use that data to his benefit… The defendant gained access to Senator Hassan’s Office by unlawfully obtaining keys from a staffer who was (at the time) still employed in the Office (Subject A). The defendant then used those keys to enter the Senator’s office alone at night…. The defendant surreptitiously installed ‘keylogger’ devices on at least six computers in Senator Hassan’s Office…. designed to record the keystrokes that Senate stafers typed on their Senate-owned computers – including the keystrokes that comprised usernames and passwords. On October 3, 2018, the defendant met with Subject A, to return Subject A’s key… defendant told Subject A to wipe down all of the computers, keyboards and computer mice…

Subject A texted: “Hey So I was able to wipe down the keys and mouse but [witness 3] was coming so I could [not] do the other thing”

The government confiscated two gmail accounts, keyloggers and two twitter accounts: @TrundleDaGreat and @CongressOfShit.

Cosko, a supporter of Democratic presidential candidate Bernie Sanders, was born to a California family with ties to Democratic California Sen. Dianne Feinstein. Republicans suggested the California Democrat leaked a letter soon before Kavanaugh’s confirmation hearing that alleged the Supreme Court justice sexually assaulted Christine Blasey Ford.

The suspect’s father, Greg Cosko, is the CEO of Hathaway Dinwiddie, a construction company that built a university building named after Feinstein’s husband. He serves on the board of San Francisco State University alongside Willie Brown, the California politician who said he helped make the career of Democratic California Sen. Kamala Harris, with an illicit affair.

As former chairman of the San Francisco Chamber of Commerce, Greg Cosko hobnobbed with then-House Minority Leader Nancy Pelosi, Feinstein and others. The elder Cosko’s adult son appears to have made inroads in Washington via an internship with Feinstein.

Luke Rosiak is the author of the new book Obstruction of Justice: How the Deep State Risked National Security to Protect the Democrats , about a computer hack on the House of Representatives.

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