The victim can still remember the stench from that attic in Ardoyne where, as a 10-year-old child, she was imprisoned. "X locked me in there for days. X wouldn't let me use the toilet. X gave me a bucket.

"I was so scared that I wet the bed. X wouldn't let me change the sheets. I had to sleep in the ones soaked with my own urine. The mattress became infested with maggots. The smell from the bucket, and the bed, was overpowering. It made me throw up.

"When I cried or screamed to get out of that room, X clasped my mouth shut. Then, X beat me with their hand and a belt [and] made me drink my own urine. This happened many times."

The victim is the middle-aged daughter of a legendary Belfast IRA commander. In her north Belfast home, she tells a story of the most appalling physical, mental and sexual abuse that occurred when she was particularly vulnerable – her father was in prison and her mother had died from cancer two years earlier.

X, the person she says carried out the abuse, is currently an elected Sinn Féin representative in the north. X is listed as such on the party's website. We are not printing either the victim's name or X's name for legal reasons.

The victim says that both Sinn Féin – including party president Gerry Adams – and the Provisional IRA have been informed of X's activities, but have taken no action to suspend or expel X from the party. X is not one of Sinn Féin's north Belfast representatives.

The victim made a statement to the PSNI almost two years ago and a police file has been forwarded to the Public Prosecution Service. "I'm disgusted that X remains a Sinn Féin elected representative and I can't understand why X hasn't been prosecuted," she says.

"The PSNI have the hospital records of my injuries, the psychiatrists' and social workers' reports, and details of social services meetings to discuss my case. As well as my statement, they have statements from my brothers. I fear that another cover-up by Sinn Féin and the authorities, similar to that which Áine Tyrell [the daughter of Gerry Adams' brother, Liam] experienced, is taking place."

The abuse took place for over a year in the late 1970s and early 1980s, when social services took her, battered and bruised, into care.

She was examined in Lissue Hospital, Co Antrim, by Dr Oliver Shanks. The Sunday Tribune has seen his report. Shanks noted that she had a cut under her left eye, two bruises on her face, and four on her trunk. Her upper thighs were covered in bruises as were the backs of her hands.

"Altogether there were 20 bruises of differing dates on [her] body," Shanks reported. There were "marks on her feet" which could have been "burns" and marks on her scalp. "X put out cigarettes on me and burned me with matches and lighters," the victim says. "Once X bought a packet of 20 cigarettes, made me smoke them until I was sick, and then forced me to eat the butts."

There was sexual abuse too. Her teachers at Ardoyne's Holy Cross school had noted her "abnormal sexual behaviour and general behaviour problems". The Sunday Tribune has seen their statements to social services. Her GP referred her to a psychiatrist in the Royal Belfast Hospital for Sick Children "because of abnormal sexual interest".

What the GP and teachers didn't know was the reason behind the 10-year-old's behaviour: "X made me come into the living room at night when everyone else was in bed. X lay on the sofa naked and drunk. I was forced to touch X sexually.

"X threatened to kill me if I didn't. X said if I was killed nobody would miss me because nobody cared about me. When I refused to touch X sexually, I was beaten until I did. X sexually violated me, using wine bottles. Once X scraped [their] nails up and down my back until I bled."

'Heavy scrabbing down her back'

Holy Cross school nurse, Eileen McErlean, reported that before the summer holidays one year, "[She] presented with very heavy scrabbing down her back" and that the child complained that X wouldn't let her leave the house.

In that house, X treated her like a slave, the victim says: "If I didn't finish my dinner, X left it there for days and I wasn't allowed to eat anything until I ate that food. Once, X filled the bath and held my head under the water until I passed out. Another time X cut off all my hair with a razor blade."

X locked her in the dog kennel in the house's backyard for three days. She says: "I was left, terrified and starving. When I banged on the walls or cried, X came out and beat me." She says that once X made her wash the kitchen floor four times with a toothbrush. Whenever she stopped, X beat her.

"Sometimes, I cried so hard during a beating that I could hardly breathe. X monitored my every move. When X sent me to the shops, X timed me. If I was back one minute late, X beat me."

Official reports seen by the Sunday Tribune show that neighbours in Ardoyne contacted social services about X's treatment of the victim. Neighbours reported hearing "screaming and beating" in the house. They reported that she was "kept in a lot", "forced to sleep in the attic", and "timed" by X when going out on a message. They noted she often had black eyes. One report stated that "on examination by the school nurse, [the victim] was found to have bruising on the left eye which she stated resulted from a fall against her bed".

In a subsequent report, the school health visitor reported she had more facial bruising and internal bruising to her left ear. The report stated that when asked about the facial bruising, the victim said she'd fallen against a coat-rail at school but had been unable to explain the internal ear bruising.

In reports, teacher Anne Tanney spoke of often seeing the victim with black eyes and bruising. She always claimed her injuries were accidental. Another teacher, Claire Higgins, reported the victim was "disturbed, disruptive and unable to make friends". She felt she was in "sheer terror" of X.

Higgins reported that X had admitted keeping her at six homework sums for seven hours until midnight "because they were not done tidily or neatly enough".

The victim says: "I didn't tell anyone X was responsible for my injuries because I was terrified of X. I was a child of 10 living in total fear."

According to social services reports seen by the Sunday Tribune, X mostly claimed that the victim's injuries were self-inflicted, although X admitted beating her in the past and also that X had allowed her to lie in wet bed sheets and had threatened to put a nappy on the 10-year-old.

Three neighbours in Ardoyne told social services they had seen the victim at the window of the house with stitches to a wound below her eye. The explanation given was that she had fallen on the street.

She was admitted to Lissue Hospital the next day under a place of safety order. A social services report states that "on admission she was tearful, anxious and a number of bruises were noted". After a case conference five days later, her name was placed on the 'at risk' register although the conference was "unable to determine" who was responsible for her injuries.

A month later, Belfast Juvenile Court granted a 'fit person order' and the Eastern Health and Social Services Department placed the victim with her grandmother. The next five years, the victim spent living with relatives or in children's homes. Still fearful, she never admitted to social services that X had beaten her. However, a social services placement committee report of 6 January 1984 states "it does appear that the injuries can be attributed to X".

After the victim was taken into care, her brother – then aged 12 – says X turned their attention on him: "It was physical, not sexual, abuse. X would beat me to a pulp with belts and wine bottles. I was scared shitless of X."

Social services report

Two months after his sister was placed in care, her brother ran away from Ardoyne to escape X, staying with his grandmother in west Belfast. A social services report noted "a similar pattern to that surrounding the victim's admission to care seems to be emerging". Her brother then went to live with relatives in the US. When he returned to Ardoyne, he says, X's abuse began again.

Another social services report noted that he was "repeatedly requested" to be placed in care and that X was putting him through "mental torture". He was taken into care from the age of 14 to 16.

But it was his sister who had suffered the most. A Nazareth Lodge children's home assessment noted: "[She] finds it difficult to sustain any type of relationship. [She] is a lonely girl who lives in constant fear of rejection."

The victim says: "X stole my childhood. I left school at 15 with no qualifications. I had severe behavioural problems. I had many failed relationships with men until I met my husband."

In spring 2008, the victim and her two brothers went to the PSNI to make statements about X. She says a police report was sent to the Public Prosecution Service seven months ago, but she is perplexed as to why X still hasn't been charged: "I want X in court. I want X to admit what was done to me. I can't move on with my life until I get justice."

Her brother says that before his sister went to the PSNI, he approached his local Sinn Féin officials. "I spoke to Seán Maguidhir and Pat McLarnon, members of the north Belfast comhairle ceantair, about the situation. I went to these people, whom I knew, because my family lives in north Belfast.

"Both Sinn Féin officials told me X would be suspended from the party pending the legal outcome of the case. They said X would be stood down as a Sinn Féin representative. We were happy with that as a family. When no action was taken, I spoke to the local IRA OC. I'm very disappointed that X continues to hold office for Sinn Féin."

The victim says: "When I went to the PSNI, another family member informed Gerry Adams face-to-face of what X had done to me. Gerry said he was aware of the stories that X had abused me, but hadn't known the details. Gerry promised to have X expelled from Sinn Féin immediately. I feel very let down by the republican movement."