NEW YORK (Reuters) - Federal prosecutors on Wednesday unveiled child pornography charges against self-help guru and accused sex trafficker Keith Raniere, just hours after a former top associate pleaded guilty to engaging in a criminal conspiracy with him.

FILE PHOTO - Nancy Salzman, exits following a hearing on charges in relation to the Albany-based organization Nxivm at the United States Federal Courthouse in Brooklyn at New York, U.S., July 25, 2018. REUTERS/Brendan McDermid

In a superseding indictment unsealed in Brooklyn federal court, prosecutors accused Raniere, founder of the Albany, New York-based organization Nxivm, of coercing a child to engage in sexual conduct to produce visual depictions of it, and of possessing child pornography between 2005 and 2018.

Raniere, who was known within Nxivm as “Vanguard,” was arrested in March 2018 on charges including sex trafficking. Prosecutors said Raniere led a group within Nxivm called DOS or “the sorority” in which women were branded with his initials, blackmailed and coerced into having sex with him.

A trial is scheduled to begin in April.

Marc Agnifilo, a lawyer for Raniere, has said his client’s sexual relationships with members were consensual, and on Wednesday denied the child pornography charges.

“If these charges were legitimate the government would have brought them a year ago,” he said in an email.

The charges were unsealed several hours after former Nxivm president Nancy Salzman, known in the organization as “Prefect,” pleaded guilty to racketeering conspiracy before U.S. District Judge Nicholas Garaufis.

Salzman, who has not reached any agreement to cooperate with prosecutors as part of her plea, admitted to hacking the email accounts of Nxivm critics and overseeing the destruction of video evidence in a civil lawsuit involving the organization.

Her daughter, Lauren Salzman, has also been charged in the case, along with actress Allison Mack, Seagram liquor heiress Clare Bronfman and Nxivm member Kathy Russell. All have pleaded not guilty.

Prosecutors have said Raniere and his associates ran “pyramid-structured” schemes, including selling expensive courses, to bring in money and new members.

They have said that members of DOS were required upon joining the group to provide so-called “collateral” that could be used against them if they tried to leave, including compromising information about family and friends, nude photographs and rights to their assets.

Only Raniere and Mack are accused of sex trafficking. Other defendants face charges including conspiracy to commit racketeering, wire fraud and identity theft.

Nxivm on its website calls itself “a community guided by humanitarian principles that seek to empower people and answer important questions about what it means to be human.”