ActBlue cofounder Matt DeBergalis invoked his Fifth Amendment right against self-incrimination multiple times on Thursday during a closed-door deposition in a congressional investigation of the Democratic fundraising platform.

The interview before the House Administration, House Judiciary, and Oversight and Government Reform committees lasted less than half an hour, according to two sources familiar with the hearing. Lawmakers had sought testimony from the cofounder of Democrats’ largest fundraising apparatus as part of a joint Republican-led inquiry into allegations that ActBlue’s fraud-prevention practices allowed fraudulent or foreign donations to enter U.S. political campaigns.