Four senior aides to Secretary of State Mike Pompeo have been subpoenaed over accusations they stonewalled an investigation into State Department Inspector General Steve Linick’s firing by President Donald Trump. “The Administration continues to cover up the real reasons for Mr. Linick’s firing by stonewalling the Committees’ investigation and refusing to engage in good faith,” a joint statement from House Foreign Affairs Chairman Eliot Engel, House Oversight Chairwoman Carolyn Maloney, and Sen. Bob Menendez reads. “That stonewalling has made today’s subpoenas necessary.”

The subpoenas were issued by Engel to Undersecretary of State for Management Brian Bulatao, Deputy Assistant Secretary of State Mike Miller, former Deputy Assistant Secretary of State Marik String, and senior adviser Toni Porter. Bulatao has been accused by Linick of pressuring him to stop investigating Pompeo’s stewardship of a Saudi Arabian arms sale and his usage of taxpayer resources. Democrats claim the others knew about the circumstances of Linick’s firing or the investigations.