As the N.F.L. was investigating his team for widespread workplace misconduct, the Washington Commanders owner Daniel Snyder directed a “shadow investigation” to interfere with and undermine its findings, a Congressional committee found.At Snyder’s behest, his legal team used private investigators to harass and intimidate witnesses, and created a 100-page dossier targeting victims, witnesses and journalists who had shared “credible public accusations of harassment” against the team.The House Committee on Oversight and Reform released a 29-page memo on Wednesday that detailed the findings of its eight-month inquiry into how the Commanders and the N.F.L. handled claims of rampant sexual harassment of the team’s female employees. The report came ahead of a hearing where the league’s commissioner, Roger Goodell, was expected to appear and face questioning.Snyder declined two requests to appear, citing a “longstanding business conflict.” At Wednesday’s hearing, Representative Carolyn B. Maloney, Democrat of New York and the chairwoman of the committee, said she planned to subpoena Snyder to provide a deposition next week.In the memo, Maloney wrote that the panel’s inquiry uncovered evidence that Snyder sought to discredit those who had made claims against the team and to create “an exculpatory narrative” that Snyder was not to blame for the misconduct, which was alleged to have taken place from 2006 to 2019, almost the entire tenure of his ownership.To that end, Snyder and his lawyers also gathered thousands of emails from Bruce Allen, who was a Commanders executive from 2009 to 2019, in an effort to blame Allen for the creation of a toxic work environment, and sought to influence the N.F.L. investigation through direct access to the league and Beth Wilkinson, the lawyer who led the league’s report, per the memo.A representative for Snyder said in a statement that the committee’s investigation was “predetermined from the beginning” and asserted that the team addressed these workplace issues “years ago.”The N.F.L. was aware of Snyder’s actions, the memo said, “but failed to take meaningful steps to prevent them.” Wilkinson’s investigation led the league to impose a $10 million team fine on Snyder and had him step back from the club’s day-to-day operations, but the N.F.L. did not ask Wilkinson to prepare a written report, a decision that has drawn scrutiny both from elected officials and former team employees who participated in the investigation.Goodell told the committee in Wednesday’s hearing that the league had “compelling reasons” to limit the Wilkinson report to an oral briefing, namely to preserve the confidentiality of its participants. “We have been open and direct about the fact that the workplace culture at the Commanders was not only unprofessional, but toxic for far too long,” Goodell said in prepared testimony. He added that there had been “substantial transformation” of the team’s office and that it “bears no resemblance to the workplace that has been described to this committee.”The committee, which said its intention was both to examine failings by the Commanders and the N.F.L. and to strengthen workplace protections for all employees, will present its findings at Wednesday’s hearing. The N.F.L. started a second investigation into the Commanders earlier this year, in response to a new allegation of sexual harassment that directly implicates Snyder in a February congressional round table. Goodell has said that the findings of that investigation, led by the lawyer Mary Jo White, will be made public.Understand the N.F.L.’s Recent ControversiesCard 1 of 8A wave of scrutiny. The most popular sports league in America is facing criticism and legal issues on several fronts, ranging from discrimination to athletes’ injuries. Here’s a look at some of the recent controversies confronting the N.F.L., its executives and teams:Allegations of potential fraud. A former team executive for the Washington Commanders claimed that the team skimmed revenue from ticket sales meant to be shared with the rest of the N.F.L. and withheld security deposits from fans. The franchise has sent 102 pages of documents rebutting the claims to the Federal Trade Commission.Sexual harassment claims. Daniel Snyder, the owner of the Commanders, is the subject of an N.F.L. inquiry after sexual harassment allegations were made against him by former employees. In July, the league fined the franchise $10 million after an investigation into allegations of harassment in the team’s front office.A demoralizing culture for women. After the 2014 Ray Rice scandal, the N.F.L. stepped up its efforts to hire and promote women. But more than 30 former staff members interviewed by The Times described a stifling corporate culture that has left many women feeling pushed aside. Six attorneys general warned the league to address the problems or it could face an investigation.The committee’s memo also cites additional examples of Snyder’s direct role in creating a workplace that Goodell acknowledged was marked by widespread disrespect and harassment. The team’s former chief operating officer told the committee that Snyder “refused to take action” against a coach who allegedly groped a public relations employee and fired female workers who engaged in consensual relationships with male football operations employees, while the men kept their jobs.In addition, The Washington Post reported that the Wilkinson investigation examined the 2009 confidential settlement of a claim that Snyder groped a female employee and asked her for sex.