The new “in-depth” programme, which is set to be released on Channel 5 later this year, is being produced by Viacom Studios.
It will feature contributions from Rachel’s mother Rose who has said she would “do anything it took to keep Rachel’s memory alive."
However, she admitted that it was “a bit heavy going” as it goes into a lot of detail.
Rose and her husband Jim recently spoke out about how they struggle with the concept of forgiveness when thinking about the man who killed their daughter in 2004.
In an interview for the podcast series Shattered Lives, Jim and Rose Callaly spoke about their memories of the day Rachel was found dead in her North Dublin home and how they view her killer today.
Mother-of-two Rachel was bludgeoned to death by her husband Joe, who was having an affair behind her back with long-time-lover Nikki Pelley.
O’Reilly, who has never admitted the crime, was found guilty of the murder and was jailed for life in in 2007.
Speaking about O'Reilly today, Jim says he can’t ever see him (Joe) showing remorse.
“He just doesn’t have that in him,” Jim said. “People have said that to me (about forgiveness) and I said, well, the ball is in his court.
"He never apologised to us for what he has done. He’d have to make the first move and then I'd have to consider it. I can't see that happening but I don’t even think about him because I don't get any consolation thinking about him.”
Rose added: "I've often thought, because I know you're supposed to forgive, that I could say the words. I would sort of wish I was the better person that I could. But you can say words but you have to mean them too and that hasn't happened.”
Rose also recalled the horrific day she discovered her daughter’s body in the bedroom of her home in the Naul, Co Dublin.
“When I got to the door it was wide open and Rachel was on the floor. It was just unbelievable. I knelt down beside her and I thought maybe she'd fallen but I knew (she was dead). She was marble cold.
“I can't remember how long I knelt beside her but I’ll never forget kneeling beside her in the room and it just felt, I can't explain the word., it was desolate. It really had a desolate feeling about it. I'll never forget the feeling. I just felt that I was the only person alive in the world.
"I remember the girl that lives up the road told me after, 'I could hear you screaming'. I didn't realise I was screaming. It's surreal. It’s like it’s happening to somebody else."
Jim remembers getting to the house "fairly quickly".
"There was a lady Garda there and she said you’d be better not go in there so I didn't."
When Joe arrived on the scene, “he just took off”, Rose said.
"He just flew into the house and he went down to the bedroom and I followed him. I always remember he looked down at Rachel and he said, which struck me as bizarre, 'Jesus Rachel, what did you do'.
"I kept thinking, 'what does he mean? Rachel is dead. Obviously, she didn't kill herself. It was as if she was the cause of it. There were books and that lying around in the bedroom and he start throwing them around..
"It was only later when I processed that (that I thought) that is a bizarre way of going on for a husband. I was waiting on him to lift Rachel up, you know, to hold her and everything but there was absolutely none of that.”
Despite all they have gone through, Rose says she and Jim remain determined to do everything in their power to keep O’Reilly behind bars.
After spending the last 14 years in prison, he is now asking for day trips to see his two children.
“I've often felt I don't want anybody in Ireland to ever forget what he done. It was a well-planned murder and she was blameless," Rose said.
“If they were to tell me he never got out again, I’d be happy.
“He’s still breathing, he still has a life, he can study or do whatever he likes. It’s the life he made for himself, but he took Rachel's life.
“He ruined our family. It's never been the same since. I realise now it can bring you closer together and it didn’t do that with us to be honest with you.
“He absolutely ruined our lives.”