A foreign citizen, Christopher Steele, was paid by Hillary Clinton and the Democratic party to interfere in the 2016 presidential election. Steele fabricated stories of Trump-Russia and funneled them to the FBI. Steele was fired from the FBI as a source for violating FBI regulations by leaking the same fabricated stories to the mainstream media. Steele was forbidden by the FBI, and the FBI prohibited by its own regulations, from doing any further work or using any information gathered by Steele.
To circumvent FBI regulations, Deputy Director Andrew McCabe, his chief legal counsel Lisa Page, and deputy counterintelligence division chief Peter Strzok arranged for Steele to pass more of his fabricated information to Bruce Ohr, who then passed it on to Pientka. Pientka filled out twelve FBI 302 interview reports citing Bruce Ohr as the source to create a paper trail intended to hide the fact that the FBI was violating its own regulations and still receiving information from Steele, the Clinton campaign, and Democratic operatives.
Bruce Ohr's wife, Nellie Ohr, likewise collaborated in writing the fabricated Trump-Russia allegations with Christopher Steele.
Pientka participated with Peter Strzok in the interview of National Security Advisor Gen. Michael Flynn. The Flynn FBI 302 interview reports of Pientka and Strzok were later altered and manipulated by Deputy Dir. Andrew McCabe. After President Trump fired FBI Director James Comey for incompetence and corruption, Special Counseled Robert Mueller used the altered interview reports to prosecute Gen. Flynn for "lying to the FBI." The original Pientka and Strzok interview reports of Flynn said that, in their judgement, Flynn answered all questions truthfully.