Almost a year to the day since Donald Trump's election victory, details about the allegations in the so-called "pee tape" dossier could be set to emerge, as the president's former longtime bodyguard Keith Schiller will be interviewed by the House Intelligence Committee about a 2013 trip his boss took to Moscow.

The trip is at the heart of the most salacious and scrutinized claims in the dossier alleging that Russia coordinated with Trump’s campaign to help him get elected.

Related: Here’s What the 'Golden Shower' Dossier Now Being Investigated by Mueller Claims About Trump and Russia

Trending: Comey’s FBI Initially Believed Clinton Was ‘Grossly Negligent’ in Handling Classified Emails

Given Schiller has been one of Trump’s closest confidants since he began working for the real estate magnate in 1999, Congressional investigators’ questions are likely to focus on more personal aspects of the dossier. In particular, that 2013 trip during the Miss Universe Pageant will be the subject of questions on Capitol Hill, according to The Washington Post.

Famously, the dossier, which was compiled by former British intelligence agent Christopher Steele, claims that on his Moscow trip Trump employed prostitutes to urinate on a hotel room bed once slept on by former President Barack Obama and first lady Michelle Obama. The room was said to have been bugged, with a videotape of the incident in the possession of Russia’s FSB security agency, effectively giving the Russian government leverage over the now president. The claim saw Steele's findings given the informal title of the “pee tape” dossier or “golden shower” dossier.

Trump has dismissed the dossier as “fake” and “totally made-up stuff” and even addressed the most salacious allegation, stating at a press conference in January that “I’m also very much of a germaphobe, by the way, believe me.” Trump also claimed that the incident could not have happened because he always warned those who accompanied him on foreign trips to be aware of hidden cameras.

Story continues

Don't miss: Sammy Sosa's White Skin Has Twitter Freaking Out (Again)

Keith Schiller, Donald Trump

Nicholas Kamm/AFP/Getty Images

The president has confirmed that Schiller was with him on that trip and has claimed that his bodyguard was mystified by the dossier’s allegations of what transpired.

“Keith was there,” Trump told The New York Times in July. “He said, ‘What kind of crap is this?’ I went there for one day for the Miss Universe contest, I turned around, I went back. It was so disgraceful. It was so disgraceful.”

Most popular: Anthony Scaramucci Is Desperately Trying to Keep His Role as a Tufts University Adviser as Students Petition

Schiller continued to work closely with Trump as head of Oval Office operations until he left the role in August. While he won't be under oath Tuesday and the testimony will be behind closed doors, making false statements to Congress can be punished by up to five years in prison.

Although dismissed by Trump, the dossier has been taken more seriously by investigators since coming to the FBI’s attention last year. Special Counsel Robert Mueller is now leading the investigation into it and recently met with its author. Founders of the firm who commissioned Steele, Fusion GPS, have also been subpoenaed to appear on Capitol Hill, although they have refused to provide testimony.

More from Newsweek