Manhattan prosecutors say a private equity executive turned his New York City apartment into a torture chamber of “grotesque sexual violence.”

Manhattan authorities said an attorney raped, assaulted and methodically humiliated six women over five months in his Midtown apartment — at times using shock collars and electric cattle prods to torture them and recording the abuse with cameras throughout his home.

The 43-year-old is accused of raping six women over five months in a depraved rampage in which he punched, waterboarded and shocked victims with a cattle prod and kept recordings of the assaults as trophies.

The killing occurred after the victim got into a fight with a second man on a downtown No. 5 train during the morning rush hour, officials said.