During his testimony before House investigators on Tuesday, Lt. Col. Alexander Vindman, the National Security Council's top Ukraine expert, said President Trump was under the impression that a different person — a longtime staffer of Rep. Devin Nunes (R-Calif.) — actually held his position, people familiar with his testimony told Politico.

Vindman said that Kashyap Patel "misrepresented" himself, and despite having no experience or expertise on Ukraine, was part of the White House's Ukraine policy discussion, Politico reports. Vindman found this out after he attended Ukrainian President Volodymyr Zelensky's inauguration in May, and was preparing to give Trump a debriefing on the event and Zelensky's plans for the future, he reportedly testified. Vindman revealed that "at the last second," his boss at the time, Fiona Hill, told him not to attend the debriefing because it might confuse Trump, who thought Patel was the top Ukraine expert.

Patel, Nunes' top staffer on the House Intelligence Committee, was known for trying to discredit Justice Department and FBI officials who investigated Russian meddling in the 2016 election, Politico reports. He joined the White House in February, and in July, was promoted to a senior counterterrorism role. Hill testified earlier this month that Trump thought Patel was in charge of the National Security Council's Ukraine policy, Politico says.

Vindman, who told investigators he's never had a conversation with Patel, also said he was told Patel ignored National Security Council procedures and put negative information about Ukraine in front of Trump, which reinforced his belief that the country was corrupt, Politico reports. It's unclear where he received this information. Read more at Politico. Catherine Garcia