Cosko faces five federal offenses: making public restricted personal information; making threats in interstate commerce; unauthorized access of a government computer; identity theft; and obstruction of justice/witness tampering.
He also is charged with two D.C. crimes: second-degree burglary and unlawful entry, according to a statement from the U.S. Attorney’s Office for the District of Columbia.
Charging documents have not been made public to this point. It is unclear whether they are under seal.
Cosko remains in police custody, and is scheduled to make his first appearance Thursday afternoon, in U.S. District Court.
According to Legistorm, a website that tracks lawmakers and Capitol Hill staffers, Cosko worked for Democratic Sen. Maggie Hassan of New Hampshire from January 2017 to May 2018 as a legislative correspondent/systems administrator.
A spokesman for Hassan declined to comment Wednesday night.
Cosko’s LinkedIn page said he assisted senior staff “with issues before the Commerce Committee including technology, telecommunications, transportation; as well as with cybersecurity matters before the Homeland Security Committee.”
“The investigation will continue and additional charges may be forthcoming,” said Capitol Police spokeswoman Eva Malecki.