In the first days of March, a team of advisers from President Trump’s new Department of Government Efficiency initiative arrived at the Southeast Washington, D.C., headquarters of the National Labor Relations Board.

The small, independent federal agency investigates and adjudicates complaints about unfair labor practices. It stores reams of potentially sensitive data, from confidential information about employees who want to form unions to proprietary business information.

The DOGE employees, who are effectively led by White House adviser and billionaire tech CEO Elon Musk, appeared to have their sights set on accessing the NLRB’s internal systems. They’ve said their unit’s overall mission is to review agency data for compliance with the new administration’s policies and to cut costs and maximize efficiency.

But according to an official whistleblower disclosure shared with Congress and other federal overseers that was obtained by NPR, subsequent interviews with the whistleblower and records of internal communications, technical staff members were alarmed about what DOGE engineers did when they were granted access, particularly when those staffers noticed a spike in data leaving the agency. It’s possible that the data included sensitive information on unions, ongoing legal cases and corporate secrets — data that four labor law experts tell NPR should almost never leave the NLRB and that has nothing to do with making the government more efficient or cutting spending.