Updated at 3:05 p.m.: Revised to include comment from Rick Perry and a DOE spokeswoman.

WASHINGTON — In the ongoing drama over allegations that President Donald Trump abused his office by asking a foreign leader to investigate one of his Democratic presidential rivals, Energy Secretary Rick Perry keeps making cameos.

The former Texas governor first was given passing reference in the whistleblower complaint against Trump over the president's July call with Ukrainian president Volodymyr Zelenskiy. Then, Perry was mentioned in House Democrats' subpoena to Trump lawyer Rudy Giuliani over the matter.

Then came the move this week by Sen. Bob Menendez, the top Democrat on the Senate Foreign Relations Committee, to question Perry directly over his interactions with Ukrainian officials.

"Given your role as the leader of the official United States delegation to the inauguration," the New Jersey Democrat wrote in a letter to Perry, referring to the Zelenskiy swearing-in that Perry attended in May, "your insight into the U.S. delegation's trip is of particular interest."

Perry hasn't been accused of wrongdoing, even as House Speaker Nancy Pelosi has moved forward with a formal impeachment inquiry against Trump.

The energy chief on Wednesday also addressed the controversy for the first time, saying briefly at an Energy Department event on artificial intelligence and energy that he is "going to work with Congress and answer all their questions," according to CNN.

Asked why he was asked to attend Zelenskiy's inauguration in Vice President Mike Pence's stead, Perry said, according to CNN: "Oh, I think it's because I'm just such a darned good Cabinet member, and very capable, and probably pretty knowledgeable about the energy industry."

Energy Department spokeswoman Shaylyn Hynes, in response to a request for comment on Wednesday about Menendez's request, added that "regardless of subject, the department is always willing to work with Congress in response to requests that follow proper procedures."

In any case, where exactly does Perry fit into what's become the biggest crisis of the Trump presidency so far? Here's a guide:

President @realDonaldTrump and the U.S. stand behind Ukrainian President @ZelenskyyUa’s goal of energy security for Ukraine and the region. @ENERGY will continue to support Ukraine and regional allies’ efforts to achieve energy independence and prosperity. pic.twitter.com/7wwXKHMoco — Rick Perry (@SecretaryPerry) September 26, 2019

How did Perry get connected to Trump's Ukraine predicament?

It all begins with the appendix of the whistleblower complaint, which details Trump's efforts to pressure his Ukrainian counterpart to dig up dirt on former vice president and Democratic presidential frontrunner Joe Biden.

The complainant alleges that Trump told Pence to cancel his trip to Ukraine to attend Zelenskiy's inauguration. The implication was that Trump didn't want such a high-level meeting until he saw how the Ukrainian "chose to act" in office, the whistleblower said.

Perry was sent to the inauguration instead — a fact that was publicly reported at the time.

The whistleblower makes no other mention of the Texan, offering no insight into Perry's knowledge or lack thereof of Trump's other communications with Ukrainian leaders. If anything, the complaint suggests that Perry was sufficiently unimportant enough to send a message to Ukraine.

Wait, Rick Perry and Ukraine — that rings a bell. Haven't they come up in the news before?

Yes, but in a very different capacity.

In July 2017, Perry fell victim to a prank call from two Russian comedians, one of whom pretended to be then-Ukrainian prime minister Volodymyr Groysman. The call, while an embarrassing lapse in vetting, covered mostly ordinary matters.

The only real gotcha was that the fake prime minister pitched Perry on using pig manure as a power source.

OK, that's random. But still, Perry is Energy Secretary. Why is he dabbling with foreign affairs in the first place? Isn't that the Secretary of State's job?

It's true that Secretary of State Mike Pompeo is the president's point person on diplomatic matters — a fact that has put Pompeo right in the middle of the Ukrainian scandal. It's also true that Perry has a far-reaching domestic portfolio at the Energy Department.

But an energy secretary's job also features lots of global work, no matter if the issue is nuclear security, scientific research or energy production. And the Texan, who also made overseas inroads as governor, has pursued that component of his job from the get-go.

Perry's schedule is littered with meetings, phone calls and events with foreign presidents, energy ministers and other government officials. Those leaders have represented myriad countries, ranging from Mexico to Saudi Arabia to Canada to Kazakhstan to, yes, Ukraine.

So has Perry connected with Ukrainian officials often?

It's hard to quantify. But the energy chief has engaged the country for some time.

He met in June 2017 with former Ukrainian president Petro Poroshenko at DOE headquarters in Washington. He met several top officials on a visit to Ukraine last November. He interfaced with a Ukrainian delegation in early May at a confab in Brussels.

Indeed, it appears that Perry has become something of a subject-matter expert on Ukraine within the Trump administration.

Politico this week highlighted an interview that a Ukrainian broadcaster did in July with U.S. Ambassador to the European Union, Gordon Sondland. In it, Sondland described himself, Perry and Kurt Volker, former special envoy to Ukraine, as the "three amigos" overseeing Ukraine-U.S. relations.

Why does Perry care about Ukraine?

The Texan is a big promoter of American energy production on the world stage. His agency has even taken to dubbing liquefied natural gas as "freedom gas," with a top aide saying the fuel gives "America's allies a diverse and affordable source of clean energy."

Perry has taken particular interest in pursuing energy independence for Eastern European countries that might otherwise be beholden to Russian fuel sources, Politico reported.

Those efforts included striking a deal to send American-mined coal to Ukraine. Perry in November cited the shipment as "just one example of America's readiness and commitment to help diversify Europe's energy markets."

What's next for Perry in the Ukraine saga?

That remains to be seen.

Menendez, the New Jersey Democrat, demanded that Perry respond by Friday to questions about his dealings with Trump and Zelenskiy. House Democrats are waiting to see how Giuliani responds to a subpoena for a multitude of records, including some Perry-related documents.

Perry could also eventually be called to testify before Congress, Politico reported, though that step hasn't yet been taken.