Author Daniel Halper asked Friday “where’s the criminal investigation” against Ghislaine Maxwell, the alleged madam of disgraced financier Jeffrey Epstein, and stressed that “transparency” from the Department of Justice is needed.

Halper, the author of “A Convenient Death: The Mysterious Demise of Jeffrey Epstein,” noted on Friday that Maxwell “has been accused of partaking” and “being an accessory to” crimes related to Epstein and told “America’s Newsroom” that “what’s shocking” is “that the Justice Department doesn't seem so keen to go after her.”

Last month, Maxwell won a critical request to delay questioning in a civil suit filed against her on the grounds that her sworn testimony could incriminate her should there be a criminal case against her in the future.

Jeffrey Epstein and Ghislaine Maxwell attend de Grisogono Sponsors The 2005 Wall Street Concert Series Benefitting Wall Street Rising, with a Performance by Rod Stewart at Cipriani Wall Street on March 15, 2005 in New York City.

Jeffrey Epstein and Ghislaine Maxwell attend de Grisogono Sponsors The 2005 Wall Street Concert Series Benefitting Wall Street Rising, with a Performance by Rod Stewart at Cipriani Wall Street on March 15, 2005 in New York City. (Photo by Joe Schildhorn/Patrick McMullan via Getty Images)

Maxwell, the daughter of late British media magnate Robert Maxwell, has been accused in court filings of facilitating a sex-trafficking operation that brought girls -- some as young as 14 -- to Epstein's Manhattan home, though she has not been formally charged with any criminal wrongdoing.

Maxwell, 58, dated Epstein more than a decade ago and became a member of his tight inner circle until his August 10 jail-cell suicide earlier this year.

Halper noted that victims are “going after her” in civil suits, but asked, “Where’s the criminal investigation?

“I think we need some transparency from the Justice Department,” he continued.

“After Jeffrey Epstein died, there were calls for investigations from the Department of Justice and there was an inclination to go after her, but since then, and it’s been a year, it’s been totally silent.”

He went on to say that “people like Ghislaine Maxwell, people like Prince Andrew, they need to answer questions.”

This week, an attorney representing some of Epstein’s accusers has slammed Prince Andrew, the financier’s longtime friend, for “hiding behind his lawyers” amid criticism from U.S. law enforcement officials who say he is refusing to cooperate with their investigation.

Halper said that attorney representing Epstein’s accusers is “correct.”

“Prince Andrew is hiding behind his lawyers and he’s hiding across the pond,” he added.

Halper also noted that Maxwell has been “hiding” and that “nobody has seen her in almost a year.”

He added, “These people need to face justice and need to tell the truth about what happened.”

Maxwell and Prince Andrew have both denied the allegations against them.

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Epstein, 66, faced sex-trafficking charges at the time of his death and was awaiting trial in a case that, if convicted, could have put him behind bars for several years.

Fox News’ Barnini Chakraborty and Fox Business’ Stephanie Pagones contributed to this report.