Despite the Trump administration’s attempts to block the House’s impeachment inquiry, witnesses have come forward to testify, unraveling a web of potentially damaging evidence.

The impeachment probe into President Trump is rapidly developing, despite the White House’s efforts to blockade witnesses and subpoenaed documents. If every witness agrees to appear the House committee will have questioned 11 Trump administration officials by the end of next week, notes Axios.

The president’s former top Russia adviser, Fiona Hill, offered devastating testimony on Monday. Hill testified that then-National Security Advisor John Bolton asked her to inform the National Security Council’s top lawyer about a rogue effort by Rudy Giuliani, EU ambassador Gordon Sondland, and acting White House chief of staff Mick Mulvaney to pressure Ukrainian officials to investigate his 2020 rival Joe Biden.

“I am not part of whatever drug deal Sondland and Mulvaney are cooking up,” Bolton instructed Hill to tell White House lawyers, according to the New York Times. Hill said Bolton earlier told her “Giuliani’s a hand grenade who’s going to blow everybody up.”

George Kent, the Deputy Assistant Secretary of State, testified on Tuesday and reportedly expressed his discontent with the improper influence of lawyer Rudy Giuliani on the White House’s Ukraine policy. Giuliani is reportedly under investigation by federal prosecutors for his business ties to Ukraine and potential violations of foreign lobbying laws.

The impeachment probe was initiated by a whistleblower complaint about a phone call between Trump and Ukrainian President Volodymyr Zelenskiy. As Citizen Truth’s Lauren von Bernuth explained last month:

“At issue is whether President Trump abused the powers of his office for personal political gain by withholding hundreds of millions in military aid from Ukraine in order to pressure Ukraine into opening an investigation into Biden, one of the leading Democratic candidates likely to face Trump in the 2020 election.

“On Sept. 23, the Washington Post reported that Trump told Mick Mulvaney, his acting chief of staff and head of the Office of Management and Budget, to withhold almost $400 million in military aid for Ukraine prior to a July 25 phone call with Ukraine’s president.”

Newly disclosed text messages and the testimony on Tuesday of George Kent, the State Department’s Ukraine expert, have revealed how Mulvaney moved to redirect leadership of Ukraine policy away from experts to the self-titled “three amigos”: diplomats Gordon Sondland and Kurt Volker, plus Energy Secretary Rick Perry, who would prioritize the plan to pressure Ukraine to investigate Biden.

Sondland is expected to testify in front of the House Committee on Thursday. Michael McKinley, who abruptly resigned as a senior adviser to Secretary of State Mike Pompeo last week, is testifying Wednesday.

Giuliani and Vice President Mike Pence have so far rejected documents requested by the House Committee. The Trump administration argues the probe is illegitimate because the House has yet to vote on authorizing a formal impeachment inquiry. House leadership has chosen to delay an official vote, arguing it would take up time and they don’t need it to make progress with witnesses. House Speaker Pelosi reportedly wants to complete the investigation by the end of the year.

The Pentagon on Tuesday also neglected to share subpoenaed documents with the House of Representative committee pursuing the inquiry citing “legal and practical concerns”, but left the possibility of disclosing the requested information in the future open.

“The Department is unable to comply with your request for documents at this time. Nevertheless, the Department respects the oversight role of the appropriate committees of Congress, and stands ready to work with your committees should there be an appropriate resolution of this matter,” the letter said, according to Reuters.