Stephen Collins -- who played the pastor/dad on "7th Heaven" -- confessed to his estranged wife he was a child molester, and it's all on tape ... a tape obtained by TMZ. And the New York Police Dept. is now conducting an active criminal investigation involving sexual contact with multiple children.

Collins -- who is in the middle of a nasty, prolonged divorce with actress Faye Grant -- revealed to her in 2012 he had molested and/or exposed himself to several underage girls years before. Collins and Grant went to a therapist where she peppered him with questions about the incidents ... and he not only answered, he was specific.

Here's what Collins didn't know at the time. Grant taped the therapy session. We're told her lawyer advised her it was legal to secretly record the conversation because in California you're allowed to secretly record conversations to gather evidence the other person committed a violent felony ... and molesting a child under the age of 14 qualifies.

We have protected the names of the victims Collins mentions on tape. As you listen ... you will hear Collins refer to a "disclosure" and a "list." This refers to a confession Collins had already made to his wife ... which triggered the therapy session.

You hear Collins flatly confess to molesting an 11-year-old New York girl -- a relative of his first wife -- saying, "There was one moment of touching where her hand, I put her hand on my penis." He also acknowledges exposing himself to the girl "a couple of times" ... he says when she was 11, 12 and 13.

Grant asks, "When you exposed yourself ... did you have an erection?" He responds, "No, I mean, no. Partial, maybe I think."

Grant then inquires about other girls. Collins mentions an L.A. girl who lived in their neighborhood, but says he tried righting the wrong by apologizing to her years later.

And then they talk about yet another girl. It's incredible ... Collins has trouble keeping the girls straight, but then he gets clear and confirms the incident. We're told this girl was also from New York and was between 12 and 13 at the time.

Read more: http://www.tmz.com/2014/10/07/stephen-collins-child-molestation-7th-heaven-audio-tape-nypd-investigation/#ixzz3HexKkGkK