NEW YORK — A private equity executive transformed his New York City apartment into a torture chamber of “grotesque sexual violence,” Manhattan prosecutors said Thursday. He is accused of raping six women over five months in a horrific rampage during which he allegedly beat, waterboarded, and shocked victims with a cattle prod while keeping videos of the crimes as souvenirs.

Ryan Hemphill, who remains in jail following his arrest last month, pleaded not guilty to a 116-count indictment accusing him with predatory sexual assault and other crimes dating back to October. According to prosecutors, the 43-year-old, who is also a lawyer, threatened victims with arrest or disappearance in order to keep them silent.

“The defendant told these survivors that he was untouchable,” Manhattan District Attorney Alvin Bragg explained. “The indictment makes clear that he was wrong.”

Hemphill sat silently in a khaki jail uniform, his shackled wrists holding a crucifix behind his back, while a prosecutor outlined his alleged crimes in graphic detail.

If convicted, Hemphill faces the rest of his life in prison. He was previously acquitted in 2015 of choking and holding a knife to his ex-girlfriend’s throat after admitting that he enjoyed strangling her during sex.

“We have reason to believe that these six victims are only the tip of the iceberg,” Manhattan Assistant District Attorney Mirah Curzer informed Judge Ann E. Scherzer.

Hemphill’s apartment near the Empire State Building was equipped with multiple surveillance cameras, and detectives have found photographs of dozens, if not hundreds, of other women, many of whom were naked and blindfolded, Curzer said.

Investigators discovered hundreds of bullets and high-capacity magazines, as well as a huge number of substances such as heroin, cocaine, amphetamines, and fentanyl, according to prosecutors.

Hemphill met the six women on websites, including those that specialise in “sugar daddy” arrangements for women looking for wealthy romantic partners, according to Curzer.

He told the women he was into role play and dominance and offered them big sums of money in exchange for sex and friendship, but he didn’t pay some of them or gave them phoney cash instead, according to Curzer.

As Hemphill got to know the women, he persuaded them to reveal their past sexual traumas, which he then purposefully reenacted while assaulting them, according to Curzer. The prosecutor claimed that he exploited some victims’ inexperience or breached boundaries that the victims had clearly defined.

Hemphill is accused of coercing victims into consuming chemicals that rendered them unable to fight back, putting handcuffs and other restraints on them, wrapping their heads and faces in duct tape, slapping and striking them, and torturing them with a cattle prod and shock collar.

Hemphill tied one victim to a bed for hours as she begged him to let her go, Curzer said.

Hemphill’s alleged conduct is “truly shocking to the conscience,” and he “has made it clear that he has no regard for the law or the courts,” according to Curzer.

To keep women silent, Hemphill boasted about his links to law enforcement and organised crime, prosecutors alleged, and stated that because the women had accepted money offers, they would be jailed.

Hemphill is accused of bribing a witness and, according to prosecutors, draughted a contract in which he agreed to pay a woman $2,000 in exchange for dismissing a complaint she filed with police. He is also accused of forcing some victims to film recordings in which they said that they had agreed to be abused.

“The power imbalance in his predatory acts could not be more clear,” Bragg told reporters. “He wielded his law degree and money as both sword and shield, coercing and silencing survivors.”

The arraignment took place just down the hall from notorious Hollywood mogul Harvey Weinstein’s rape case.

Scherzer ordered Hemphill to remain in jail without bail after prosecutors expressed worry that his situation, combined with his money and connections — including a history of philanthropy and family real estate holdings — would provide him with the means and incentive to flee the country.

Hemphill’s lawyer, a public defence assigned to represent him at least until his arraignment, had requested Scherzer to admit him to a rehabilitation facility to address his substance abuse concerns.

Scherzer concluded that, given the facts presented by prosecutors, “including efforts to dissuade by force and threats to witnesses from testifying against him,” jailing Hemphill was the only option to assure his return to court.

The court stated that Hemphill’s claimed actions “shows his extent to which he’s willing to go to protect himself from facing these charges.”