The LAPD is also re-opening their own investigation into Collins, and will be collaborating with New York authorities.
Law enforcement in California received the therapy session recordings two years ago but closed their case after finding 'no verified victim'.
In the recordings, Collins mentions exposing himself to a niece of an LA neighbor.
The startling revelation has led to the actor's firing from the movie Ted 2, just a few days after he excitedly tweeted about getting a small role in the Mark Wahlberg comedy, Entertainment Weekly reports.
The 67-year-old actor, who also appeared in the first Star Trek movie in 1979, allegedly made a written confession to his now ex-wife Faye Grant in 2012, which sparked the therapy session.
Grant secretly recorded the session under the advisement of her lawyer, who told her it was legal in California to record conversations in order to gather evidence on a person who has committed a violent felony.
In the recording, a man with Collins' distinct voice admits exposing himself to an 11-year-old relative of his first wife Marjorie Weinman. Collins and Weinman divorced in 1978. He also confessed to touching the young relative.
Collins with the cast of 7th Heaven
That incident of molestation was actually reported in 2012, and can still be prosecuted since the statute of limitations starts at the date of reporting.
Collins goes on to admit exposing himself to several others girls.
He says he exposed one girl "a couple of times" when she was 11, 12 and 13.
"When you exposed yourself...did you have an erection?" Grant then asks. "No, I mean, no. Partial, maybe, I think," Collins responds.
Collins says he also exposed himself to a girl who lived in their Los Angeles neighbourhood, who he tried apologizing to years later, and a New York girl who was 12 or 13 at the time.
An NYPD source has confirmed to TMZ that they are in possession of the tape, and last Wednesday two members of their Special Victims Unit flew to LA to interview Grant.
They allegedly questioned her about the tape and other potential witnesses.
Emails to the NYPD and Collins' representation were not immediately returned Tuesday morning.
Collins announced his divorce from Grant in May 2012, issuing a statement saying they were 'moving forward separately in our lives'.
"She has been my dearest friend and a loving mother," Collins said. "I know that we'll go through this process in a way that honors our family."
The divorce papers came as a shock to Grant who said she was both surprised and devastated.
"I wish him the very best in whatever path he chooses to take. Twenty-seven years of marriage in Hollywood is the equivalent of 189 dog years. I was exhausted," she responded.
Their seemingly amicable split quickly deteriorated, however, once they started dividing up the assets.
In their highly contentious divorce proceedings, Grant argued that she had stayed home during her peak acting years to raise their daughter and now couldn't book a job to support herself.
Meanwhile, Collins was raking in acting job after acting job making nearly $500,000 just in 2013 for appearances on the TV shows Revolution, Devious Maids, Scandal and The Fosters.
Grant said she grew used to upper-class living during her nearly three decades married to Collins, when they made between $US1 million and $US3 million a year.
She asked for an unspecified amount of spousal support, half of their $6million bank account and half the value of their two properties in Brentwood, California.
Collins next role was in American Repertory Theater's production of O.P.C' alongside Oscar-winner Melissa Leo, but he dropped out two weeks ago due to 'scheduling conflicts'
Collins was previously held a position on the National Board of the Screen Actors Guild but resigned today following the news of the investigation, a SAG/AFTRA official told TMZ.
