(CNN) As Energy Secretary Rick Perry prepares to leave office in December, it appears he could largely avoid tough questions from reporters and lawmakers about his role in the events impeachment investigators are focused on, with department staffers even apparently using a decoy vehicle to shield him from press questions.

Perry -- one of the self-styled "Three Amigos" leading US relations with Ukraine -- has declined to cooperate with a congressional subpoena, neither providing documents nor testifying to impeachment investigators.

Key questions about what he knew and when have gone unanswered, and Perry's aides appear to have shielded him on multiple occasions from questions about revelations in this week's testimony.

Fellow amigos Gordon Sondland and Kurt Volker, both American diplomats, testified to Congress about Perry's role in a consequential July meeting and his communication with Rudy Giuliani, the private attorney to President Donald Trump who urged the Ukrainians to announce an investigation linked to Democratic presidential candidate Joe Biden and his son Hunter.

Perry spoke to reporters on a conference call Thursday afternoon for a plastics-related announcement but dodged questions about his knowledge of the Ukraine-related events. His spokeswoman brushed aside a question that was not on the plastics issue.

"We're going to keep the call on topic, so we're going to move on from that," spokeswoman Shaylyn Hynes said.

After fielding a question on the plastics program, the moderator announced there were no remaining questions and ended the call, before a CNN reporter could question Perry.

"We were told by the moderator there were no questions left -- and from the beginning of the call we were having technical difficulties," spokeswoman Kelly Love explained on Friday. She declined to make Perry available for an interview Friday.

In a telephone conversation with Fox and Friends that aired Friday, Trump urged Perry to speak out.

"I'd like Rick to make a statement and Rick would make his debut," he said.

Perry avoided reporters' questions at two speeches he delivered earlier in the week. When he spoke to the US Chamber of Commerce on Tuesday, Energy Department officials shielded him from reporters by sending what appeared to be an empty decoy SUV driven by his security officers to the building's front door while Perry slipped through a different door.

Later that day, Perry, who has announced he plans to leave his post in December, delivered a farewell address to Energy Department employees. The department told CNN the farewell address was an employee-only event, but provided an online video stream.

Before this week's testimony, he largely evaded reporters at an event in Saudi Arabia known as the "Davos in the Desert" and when CNN confronted him at an artificial intelligence conference in Washington on November 5 he avoided questions by slipping out a back door.

This week, testimony from US diplomats refuted the claim from Perry's office that he was unaware of the President's interest in the Biden investigation.

Sondland, the US ambassador to the European Union, testified that Perry played an important role in gathering officials for a July 10 meeting to discuss future communications between Trump and the Ukrainian President. At that meeting, other witnesses testified that Sondland raised the request for investigations.

Perry has not addressed what he heard in the room.

Several Democrats have called on Perry to testify -- including Rep. Don Beyer, a Virginia Democrat -- who said Perry and other administration officials' "refusal to testify is utterly damning." Republican Rep. Francis Rooney, of Florida, has also called on Perry to obey the subpoena.

Perry's recent interviews have been mostly with conservative media outlets. He said in an interview with Sinclair earlier this month that he did not hear the topic come up at another meeting, also on July 10, with the US and Ukrainian national security advisers, although witnesses have testified it did.

Sondland also testified about Perry's role -- at least initially -- as a conduit between Giuliani and the so-called amigos.

"Mr. Giuliani conveyed to Secretary Perry, Ambassador Volker, and others that President Trump wanted a public statement from (Ukrainian) President (Volodymyr) Zelensky committing to investigations of Burisma and the 2016 election," Sondland testified. "Mr. Giuliani expressed those requests directly to the Ukrainians and Mr. Giuliani also expressed those requests directly to us. We all understood that these prerequisites for the White House call and the ... White House meeting reflected President Trump's desires and requirements."

Perry has said that the he never heard the Biden name raised, but has not specified whether he heard a request for investigations. His spokesperson has repeatedly insisted Perry never heard "Burisma," the name of the Ukrainian company on whose board Biden's son sat, either. Sondland and Volker -- the other two amigos -- both testified they came to understand investigations into Burisma related to Biden, raising unanswered questions about how Perry could have been unaware.

Perry recounted the call with Giuliani to the Wall Street Journal in mid-October: "And as I recall the conversation, he said, 'Look, the President is really concerned that there are people in Ukraine that tried to beat him during this presidential election. ... He thinks they're corrupt and ... that there are still people over there engaged that are absolutely corrupt.' "

The Journal reported Perry said Giuliani did not make any specific demands on that call.

In a separate interview with a Christian television network, Perry spoke in very broad terms: "Corruption was talked about in the country but it was always a relatively vague term of, you know, the oligarchs and this and that and what have you."

On Friday, Fox News reported it would air an interview with Perry over the weekend that it will address the Sondland testimony. In a promotional clip released Friday, Perry is not heard discussing Sondland's testimony, but says Trump "will muscle right on through" the impeachment allegations.

Hynes, the spokeswoman for Perry, said in a statement that Sondland "misrepresented" Perry's conversations with Giuliani.

"At no point before, during or after that phone call did the words 'Biden' or 'Burisma' ever come up in the presence of Secretary Perry," she said.

Perry has also not addressed the allegation that he gave the list of energy experts he handed directly to Zelensky at a spring meeting, which US diplomat David Holmes described in his testimony Thursday.

Perry denied to reporters in early October when visiting Lithuania that he recommended specific names for a supervisory board that oversees Ukraine's state-run gas company, but said he "gave recommendations at the request of the Ukrainian government and will continue to."

Holmes said he did not see the names on the list, but that the move surprised embassy officials.