An outgoing Republican congressman accused billionaire Leon Black and David Copperfield, the illusionist, of being co-conspirators of the accused late sex trafficker Jeffrey Epstein, and repeated a call for the Department of Justice to launch an immediate investigation into the men, among others.

Thomas Massie, a Kentucky Republican who recently lost his primary to a challenger backed by Donald Trump, named several friends and associates of Epstein on the floor of the House in his bid to “shame” the Department of Justice to investigate a group of men and one woman who Massie called “perpetrators” of Epstein’s crimes. He also noted that, nearly one year after Trump signed the Epstein Transparency Act, which led to the release of millions of so-called “Epstein files”, millions more have yet to be publicly disclosed.

“The government continues to withhold over three million files” Massie said on Monday. “That’s why we’ve introduced the Epstein Files Transparency Act II, to bring the fight to the state courts, accountability to the Department of Justice and closure for survivors.”

“We want perpetrators of these crimes to be investigated and prosecuted” he added. Massie called the individuals “co-conspirators” on his Instagram account.

Black, the New York private equity investor who paid Epstein tens of millions of dollars in fees, is separately facing a threat of being held in contempt of Congress because of an ongoing standoff over demands that he appear to testify before the House oversight committee later this week, on 3 September.

Black has not yet confirmed his appearance before the committee, according to a person familiar with the matter. Black’s spokesperson did not immediately respond to a request for comment on the scheduled hearing or Massie’s comments.

Black has described his work for Epstein as tax and estate-planning services. In a previous statement before the oversight committee in June, Black wrote of his relationship with Epstein: “I did not know about this nefarious activity until Epstein was charged with trafficking in July 2019.” But Black acknowledged that he did know about Epstein pleading guilty in “2008 to state charges relating to prostitution involving a minor”.

The chairman of the House oversight committee, the Republican James Comer, has previously said he would hold Black in contempt if he did not fully cooperate with his panel’s ongoing investigation into Epstein, including by handing over subpoenaed documents.

Susan Estrich, Black’s lawyer, has rejected Comer’s assertions that Black has not been cooperative and has said that Black was being targeted in a “political witch hunt”.

Epstein’s former lawyer, Alan Dershowitz, has also not yet confirmed his appearance before the oversight committee, according to a person familiar with the matter. Dershowitz’s appearance was scheduled to take place on Wednesday. Dershowitz told the Guardian on Tuesday that he was “working on a date”.

FBI agents investigating Copperfield in 2007 said that “a clear connection” existed between the famous illusionist and Epstein, according to documents released by the Department of Justice earlier this year. Copperfield’s lawyers have previously denied he was friends with Epstein. Lawyers for the illusionist did not respond to a request for comment on Massie’s comments, accusing Copperfield of being an Epstein co-conspirator.

In a post on X on Tuesday morning, Massie said that he, along with Representatives Ro Khanna and Teresa Leger Fernández had launched a “discharge petition to collect 218 signatures” to force a vote on the new Act.

The White House did not immediately respond to a request for comment.