Washington, DC – Capitol police officers have arrested the man who released the private telephone numbers and addresses of Senate Judiciary Committee members during the hearings about U.S. Supreme Court nominee Brett Kavanaugh.

A former co-worker spotted 27-year-old Jackson Cosko in U.S. Senator Maggie Hassan’s (D-New Hampshire) office in the Dirksen Senate Office Building typing on a computer after 10 p.m. on Tuesday, WTOP reported.

Cosko was previously asked to resign from Hassan’s office, and did not have permission to be there.

Police said he accessed the computer using another staffer’s login information.

A website that tracks lawmakers and Capitol Hill staffers reported that Cosko was employed by Hassan from January of 2017 until May of 2018 as a legislative correspondent/systems administrator, CBS News reported.

A spokesman for Hassan’s office told The Washington Times that Cosko was asked to resign “for failing to follow office procedures.” However, they said they did not see him as a “risk.”

After he was seen using a computer on Oct. 2, Cosko left the office building at 10:21 p.m. and headed toward Union Station, according to surveillance video.

Later, he sent a threatening email to the Hassan staffer who caught him, WTOP reported. The staffer contacted the police about the threat.

An affidavit from U.S. Capitol Police Captain Jason Bell said the subject line of Cosko’s email carried the header “I own EVERYTHING.”

“If you tell anyone I will leak it all. Emails signal conversations gmails. Senators children’s health information and socials,” the email read, according to charging documents.

“Signal conversations” refers to a messaging application. “Socials” refers to the children’s social security numbers, authorities said.

Cosko was arrested and charged with five federal offenses and two crimes in the District of Columbia, WTOP reported.

Federal charges included making public restricted personal information, making threats in interstate commerce, unauthorized access of a government computer, identity theft, and obstruction of justice/witness tampering.

The U.S. Attorney’s Office for the District of Columbia released a statement that said Cosko had also been charged with second-degree burglary and unlawful entry, WTOP reported.

Cosko was employed by U.S. Representative Sheila Jackson Lee (D-Texas) when he committed the alleged crimes. Jackson Lee is a staunch opponent of Kavanaugh’s nomination.

Jackson Lee’s office told FOX News that Cosko had only been employed by their congressional office for a few months, but that he had been terminated after he was accused of doxxing.

Jackson Lee’s chief of staff, Glenn Rushing, called the incident “unfortunate” and told FOX News that Cosko’s former employer’s office was cooperating with law enforcement.

Before he worked for Hassan, Cosko also worked for U.S. Senator Barbara Boxer (D-California) and U.S. Senator Diane Feinstein (D-California), who is the minority leader of the committee to whom the doxxed senators belonged.

Cosko described himself as a “Democratic Political Professional & Cybersecurity Graduate Student” on his LinkedIn page, according to FOX News.

Police have linked Cosko to the doxxing of U.S. Senators Lindsey Graham, Mike Lee, and Orrin Hatch, The Washington Times reported. Personal information of all three senators was posted to their Wikipedia pages on Sept. 27 in the midst of the contentious Kavanaugh hearings.

The publication of the senators’ private information was caught by a Twitter bot that monitors changes made to congressional Wikipedia pages. According to the bot, the information was posted from a computer in the U.S. House of Representatives, FOX News reported.

Senate Majority Leader Mitch McConnell (R-Kentucky) said Wednesday that senators would not be intimidated out of doing their jobs, CBS News reported.

He referred to protesters stalking U.S. Senator Ted Cruz (R-Texas) and his wife at dinner, protesters blocking senators’ car doors, and some even camping out at senators’ homes and offices.

“There is no chance in the world they’re going to scare us out of doing our duty,” McConnell announced on the floor of the Senate, and said that the vote on Kavanaugh’s nomination would move forward this week.

Cosko appeared in federal court on Oct. 4 and was ordered held until a detention hearing on Oct. 9, which will likely occur after the votes on the Kavanaugh nomination have been concluded.