A young woman has described the moment she discovered at the age of 14 that her dad was one of Ireland's most notorious serial killers.
Ella Porter (18) said that she was horrified to discover her father was a "monster".
Now she is considering confronting jailed killer Mark Nash.
Although she was close to her mother growing up, she never knew the true identity of her father.
English-born Nash is currently serving several life sentences for the 1997 murders of a young couple at their home in Roscommon and the vicious killings of two older women at Grangegorman in Dublin.
Ella Porter and partner Daisy Cooper
Nash left his 10-month-old daughter Ella in the rural Roscommon house on August 16, 1997 after he stabbed Catherine Doyle a total of 16 times, stabbed her husband Carl Doyle six times in the heart and left his girlfriend Sarah Jane Doyle for dead after hitting her over the head with a stove handle and pushing her down the stairs.
There were six young children in the house at the time of the killings.
Ella's mother Lucy, who was not in a relationship with Nash at the time, brought her daughter to live in the UK soon after the murders.
In an interview with the Irish Daily Star, Ella said she thought she just had a "deadbeat dad".
"For the first 14 years I was actually really happy," Ella said.
"It was difficult knowing that all my friends had dads at home who would look after them.
"My granddad was the one who looked after me if my mum wasn't around.
"I never really thought about where [Nash] was," she continued.
"I just figured that he was a deadbeat dad or that he was dead and my mother didn't want to talk about it because it was a bit upsetting for everyone.
"I was very close to my mum - she wanted me to grow up and have a normal childhood."
Ella said when she finally found out who her father was at the age of 14, she was "shocked".
After hearing pieces of the story from her mother, Ella's grandfather brought her to Paris and sat her down to tell her the full truth.
"As unreal as it seems that he could have done something so horrible, it felt all the more personal because I was there," she said.
"He was meant to be looking after me, instead he chose to do all these things to these people and he just left me there alone.
"That was all the more personal for me, because what kind of father does that to their child?"
Ella told the paper she began counselling after turning to alcohol at the age of 14.
She also said she hasn't ruled out coming to visit her father in prison in Ireland, to confront him about his actions 18 years ago.
"I just want to know what brought him to think he could do that and get away with it," she said.
"I do think he's a monster.
"There have been a lot of times where I have thought about facing him in prison," she added.
"But I don't want it to be like a family reunion where it's all smiles and we wear happy faces and hug each other.
"I want to ask him what sort of sick person could do this to other people's families. He's ruined the lives of not just the people he's murdered but their families and my family.
"I want him to know that I am never going to forgive him and that his daughter hates him."
The teenager has moved on with her life and has a girlfriend Daisy Cooper.
"Starting a new relationship with Daisy and getting to grips with what he [Nash] has done has helped me a lot.
"I have good days and bads - the good days are really good and the bad days, well they're really bad."