NEW YORK, United States - A US con man who sexually manipulated female students at a New York college after moving into his daughter's dorm room was sentenced to 60 years in prison Friday.

Lawrence Ray was convicted in April last year of running a cult-like ring that extracted millions of dollars from victims and forced one into prostitution.

He was found guilty on 15 counts, including racketeering, violent assault, extortion, sex trafficking, forced labor, tax evasion and money laundering.

"It was sadism. Pure and simple," US media quoted Judge Lewis Liman as saying, describing the 63-year-old as an "evil genius" as he handed down an effective life term.

Ray's crimes started in 2010 when he moved into his daughter's dorm at Sarah Lawrence College, a small liberal arts school in New York City's Bronxville suburb.

Prosecutors said Ray portrayed himself as a father figure, gaining the trust of his daughter's friends before subjecting them to psychological and physical abuse.

His tactics included sleep deprivation, sexual humiliation, verbal abuse, and threats of violence and criminal legal action.

Ray -- born Lawrence Grecco -- exploited his victims' mental health difficulties and alienated them from their families, his trial in Manhattan heard.

Through manipulation and abuse, he extracted false confessions from victims about fake damages they had caused him.

The victims then paid him, including from their parents' savings, by borrowing money from acquaintances and through selling real estate they owned.

They also performed "extensive physical labor" for him on one of his relatives' properties, sometimes in the middle of the night for no pay.

Ray collected sexually explicit photographs and other personal information from one victim which he then used to coerce her into commercial sex acts, from which he collected millions of dollars.

On one occasion, Ray tied his victim to a chair, placed a plastic bag over her head, and nearly suffocated her.

The convict laundered his criminal proceeds through an internet domain business and evaded paying taxes on the money, which he also shared with at least two associates.

His crimes lasted about a decade.

Reacting to the sentence, prosecutor Damian Williams, the United States Attorney for the Southern District of New York, described Ray as "a monster."

"For years, he inflicted brutal and lifelong harm on innocent victims. He groomed them and abused them into submission for his own gain," Williams said.

Prosecutors had requested a life sentence while Ray's defense attorneys asked for the mandatory minimum of 15 years.

A co-defendant of Ray's, Isabella Pollok, is due to be sentenced next month.