This case study is drawn from my involvement in a case where a young child, known as X, gave evidence at various stages in the criminal investigation of sexual assault, including anal rape of herself by her stepfather B, which he was found (in a contested trial) to have committed when she was under 3 years of age.

Following his conviction, 33-year-old B appealed both the conviction and his sentence of life imprisonment with a minimum of 20 years before consideration of his parole.

Matters had come to light after X and her two sisters were placed in foster care after the violent death of her brother. When getting dressed, X spontaneously remarked to her foster carer Mrs E that her dad rubbed her ‘fanny’. The conversation was noted and reported to Social Services, who involved a child protection officer, K. In a visit to the foster home, K spoke to X and asked about telling Mrs E about B touching her. There was some confusion and K finally asked whether B had touched her in her genital area – using hand gestures for clarification. X shook her head in response. The police file was closed then, in the absence of any verbal evidence from X.

However, some months later, during a hospital assessment in connection with care proceedings, the question of sexual abuse emerged again; X was just over 3 years old. In the presence of a consultant psychiatrist and her colleague, X made very clear references to experiences of a sexual nature involving her stepfather B, which she said were witnessed by her mother. Following a subsequent examination by a senior paediatrician when X had said that B hurt her, an ABE interview was conducted and recorded by officer K.

During that interview, X reiterated her account of sexual molestation and clearly indicated that, among other things, B had penetrated her anus with his ‘willy’ and that her mother told him to stop – ‘but he didn't stop’. K asked her, ‘What did he do?’. X replied, ‘Put it back.’ K suggested, ‘In his trousers?’ X said, ‘No, back in here …’, gesturing with her hand to point to her bottom.

Experts, including me, were engaged to provide an opinion as to X's competence to act as a witness in a jury trial. The expert instructed by the defence team cited several reasons by way of challenge to the prosecution case – the limited ability of X to understand; her age; her developmental difficulties; the passage of time between her first complaint and the ABE interview; and her exposure to flawed interviews – but with the caveat that she appeared to understand questions that were put to her and to give answers that could be understood. My evidence that X had the capacity ‘to give cogent evidence of her own remembered experience’ was cited in the appeal judgment. The trial judge had found that this very young child was competent and after reviewing the evidence the appellate judges supported his finding.

During cross-examination via a video link, this 4-year-old child was tested at length about her understanding of truth and lies, she was reminded of officer K's visit to the foster home before her third birthday, when she had indicated by shaking her head that B had not hurt her, and it was put to her that she was telling the truth then, when she had shaken her head. It was then put to her that her older sister had told her to tell lies. She denied that each time she was asked to admit it.

There came a point in the lengthy cross-examination when defence counsel asked her what B had done and she did not answer. I recall that this question was framed and re-framed several times, but X remained silent. The judge was invited to dismiss the child's evidence as she could not provide an answer that could be understood. The judge disagreed and replied that it was open to the jury to interpret her silence.

At the Court of Appeal hearing, the judges had the opportunity to review all the evidence. In an important observation the appellate judges found that, ‘Despite justified concerns about some aspects of the way in which it was conducted, the ABE interview shows an utterly guileless child, too naïve and innocent for any deficiencies in her evidence to remain undiscovered, speaking in matter-of-fact terms. She was indeed a competent and compelling witness.’

A teacher became concerned about a 9-year-old child, Jenny. An outgoing and confident child, she had changed suddenly to become quiet, distracted and seemingly unable to engage in lessons or with the other children in playtime. She seemed tired and pale and withdrawn. She was noted to be preoccupied with the contents of her desk.

Looking through Jenny's desk while the children were at lunch break, the teacher found a home-made diary. It was assumed that the diary was Jenny's own work. On some pages Jenny had drawn pictures resembling male genitals in an aroused state and had written words that were sexual in nature and badly spelled – Jenny was an excellent speller as a rule. The teacher photocopied the pages and replaced the book in Jenny's desk.

The teacher brought her concerns to the designated child protection teacher, who initiated the routine child protection procedures. Jenny's mother was asked to come to the school as a matter of urgency, where she met the duty social worker and the designated teacher, who explained their concerns and showed her the written material.

Jenny's mother denied all knowledge but she confirmed that Jenny had been sullen, quiet and nervous at home. She was sleeping poorly and had been found hiding in a kitchen cupboard late at night.

Jenny was brought to the meeting room and her mother explained what it was all about. Jenny was silent for a few seconds before she denied any knowledge of the diary: ‘It must be someone else's’. She clammed up and refused to speak or respond to any approach.

A joint police and social work investigation included a search of her bedroom, where more sheets of paper with sexual words and drawings were found hidden under her bed. An ABE interview was arranged and Jenny came with her mother. She denied knowing about the writings found in her bedroom: ‘They must be someone else's’. She refused to speak and her face remained blank; her gaze was fixed. The interview was terminated and I was contacted to consult to the child protection team.

After discussion with the mother, who was a single parent with three children older than Jenny, the question was raised as to Jenny's safety at home or in the immediate environment and she was moved to stay with her maternal aunt. All four children would stay over at weekends at their father's small flat, taking turns one at a time. This had been the pattern since Jenny was 5 years old, when her parents split up. Jenny's contact with her dad was suspended during the investigation.

She continued to attend school and other children would report that Jenny was crying in the toilets. Jenny's teacher reminded her that she could come and talk about her worries any time and she gave her a code word to use when she wanted to talk.

A further ABE interview was arranged and I helped to plan the process but remained behind the glass of a two-way mirror. Jenny's aunt attended with her and remained in the room, facilitating the process of building rapport. It was stated that the meeting was needed to help Jenny to help the others in Jenny's family to keep her safe. The writings and drawings had been found and they seemed to be a way for Jenny to get help. She was asked who in her family – brothers, sister, mum, dad – would be able to make the best guess as to what was going on. She began crying, and she asked whether her dad had been told anything. Was that a problem for her? Still crying she said she had promised her dad to keep a secret and he would kill himself if she told – and that would be her fault. So, she couldn't say anything. Her father was arrested and he denied any wrongdoing and he ‘knew nothing about any secrets’.

Having been a consultant to the investigation team, I prepared a report dealing with Jenny's competence as a witness, her mental health risks if she were to be called to give evidence and her reliability.

During the 15 months awaiting trial, a senior social worker spoke to Jenny and explained that, although she hadn't broken her promise, it would be really important to talk about her worries about anyone, even her dad, and that if people knew for sure about who had done what, then they could be helped and looked after, because nobody needed to die. Jenny tearfully agreed to make a full statement in another interview.

I studied the recording of this last interview to deal with the defendant's complaint regarding undue influence on the part of the social worker. Given the evidence from Jenny's writings and her concern for her father's life, coupled with her determined refusal to articulate what had already been implied, it was argued that the child could not recover her well-being without such an intervention.

The clarity of her account of the sexual abuse by her father during her monthly visits to his flat was effective in confronting him and enabling him to admit to the offences that he had committed progressively over a 1-year period. Jenny was spared the ordeal of being cross-examined and feeling responsible for her father.

A 10-year-old boy from a Nigerian family based in the UK, Joseph had been in foster care for 3 years. He had infrequent contact with his mother, who was serving a prison sentence related to illegal drug supply. His older sisters were placed with a maternal aunt and he enjoyed his visits to them and frequently asked if he could live with them – but they were lacking sufficient space to take him in. He was unhappy in his foster home and complained to everyone – teachers, aunt, mum, social worker – that the older children in the family bullied him with racist names. This was always denied by his carers, who were Ugandan Asians, and the assumption that the placement was a good cultural fit lent support to the carers’ assertions that he was lying.

On his return to school after the Easter break, he approached his class teacher and tearfully told her that he had been made to do bad things in the foster home. He gave no details to the teacher. The child protection team set up an ABE interview after speaking to the foster parents, who denied all knowledge and suggested that this was just another tactic by Joseph to get a move to his aunt's home.

Joseph was very anxious about giving his account of ‘the bad things’ because he was afraid of how he would be treated when he went home to the foster family. A new placement was arranged as an emergency with a White British family. Duly reassured, Joseph told the child protection officer about being forced to perform sexual acts by two teenage boys who were the sons of the foster carers. These acts amounted to torture as he described them.

He said that he screamed for help, but his foster dad called out to him to make less noise and never came near to find out why he was screaming. In great distress he gave details of the things he was made to endure. He thought they had filmed him and said they would put the pictures on the internet. He said they told him he was being punished for calling them bullies.

Medical examination revealed bruising that was consistent with his account of being tied and strangled. The doctor also noted some cuts on his forearms, which he admitted that he had done to himself.

The teenage boys were arrested and duly charged. The male foster carer was also charged with neglect of his duty of care.

I was asked to consider the evidence arising from the investigation, including the ABE interview, and express an opinion as to Joseph's competence as a witness and his emotional vulnerability in the context of a trial where he would be subjected to cross-examination. I was also asked to give general notes for a potential jury on indicators of veracity. Joseph was certainly competent, and the analysis of the evidential material did not reveal any flaws in the investigative processes. All the accused denied the charges.

In the event, Joseph was cross-examined by video link. He was accused of making up lies and deliberately bruising himself to persuade the social workers to move him to join his sisters. He broke down under this pressure.

The accused teenagers did not go into the witness box, but their father did. He was very persuasive and in his defence he relied on his long-standing reputation as a foster carer with many positive references in support.

The jury found all the accused not guilty.

The impact of those verdicts on Joseph was profound in respect of his mental health (especially self-harming) and he required a great deal of support until his mother's release from prison – which allowed him to live with her again.

A 13-year-old girl, Suzy, with severe cognitive impairment (IQ in the low 50s) ran away from home to her aunt's home nearby. She was in a very distressed state and she was without underwear. She showed her aunt where her dad had beaten her back and where he had hurt her genital area and anus. Her language was poorly developed; she struggled to convey her meaning verbally.

Her aunt called the police. Several days passed before a child protection investigation got under way. Suzy's teacher from her special school was prepared to support Suzy during an ABE interview. During the interview in an unfamiliar place, even with her teacher's support, Suzy struggled to speak at all.

Suzy had been medically examined promptly, before this interview, to ascertain whether there was any DNA present, and the forensic examiner reported that Suzy had scarring on her back and buttocks and anal scarring consistent with previous anal abuse. The examination had disturbed Suzy, who became overwhelmed with panic. Tests did not find any DNA evidence.

Notwithstanding the challenge that such an interview would create, the interviewing officer, social worker and teacher spent time establishing rapport by engaging Suzy in simple discussion about ordinary things – what were her favourite things, the names of her friends in class, etc. They established the words for different parts of the body using an illustrated educational cartoon book that was neutral in tone and did not reference any form of abuse. The injuries that had been found on her body indicated that some pattern of physical abuse, including anal abuse, had a significant history, but they decided to focus on the most recent events that had caused her to run away.

This was concentrated work which had a slow pace and at times Suzy would freeze as if she were re-experiencing her pain. The temptation to lead her was avoided and using the newly found words, Suzy was able to convey what her father had done to her.

She was asked to recall any words her dad said to her. She remembered the words but did not know their meaning. She was asked whether her mother knew about it. She said dad would lock the door to keep mum out. She added that he told her to stay quiet, to make no noise.

I was instructed to review the evidence and provide an opinion as to Suzy's competence as a witness. Because of the use of visual material to enable Suzy to make her statement during the ABE interview, I was asked to comment on whether this had compromised the validity of the interview. The lawyer from the Crown Prosecution Service (CPS) anticipated difficulties in proceeding to trial and doubted whether Suzy would cope emotionally with cross-examination as a witness to fact.

I prepared a detailed report to substantiate his opinions in relation to witness competence and process validity and added guidance notes to give indicators of veracity, which might assist the jury in the event of a contested trial.

Suzy's father denied the charges. He did not go into the witness box and he relied on Suzy failing to convince the jury.

The judge ruled on the special measures to be implemented – which included a video link, the use of an intermediary during cross-examination, the removal of wigs, agreed timings to give Suzy sufficient breaks in case of her distress, and cross-examination questions prepared in conjunction with the intermediary in advance, for approval by the judge. (It should be noted that the role of the intermediary is to facilitate the witness responses but intermediaries are independent of both sides and do not act to support or reinforce the witness's case.)

In the event, the jury found the defendant guilty on all the charges against him and he was sentenced to 13-year imprisonment. My report was also provided to the family court to assist with care proceedings.

A single mother of two young children – a 4-year-old girl and a 6-month-old boy – called 999 to get help for the baby, who had ‘stopped breathing’. The mother was the only adult at home – her first language was Somali. Her husband had been killed over a year ago when they were refugees fleeing the fighting. Her English was poor. The ambulance team arrived promptly but their attempts at resuscitation were unsuccessful.

At post-mortem, the findings in the baby's brain suggested injury caused by extreme shaking. When questioned with an interpreter, the mother said they had all been watching children's TV on the settee and the baby got up and fell onto a rug on the floor – hitting his head. The only other witness was the little girl.

The mother denied shaking her baby and would only say that the baby got up and fell on the floor. She was distraught and the interview was frequently interrupted by the interpreter, who was partisan to the mother.

The little girl, who was present when the incident took place, was interviewed 2 months later and I was asked to review the video recording. Her English was adequate and she seemed to understand what the police officer was saying. She was fidgety and easily distracted. She did not know where the ambulanceman and the lady had taken the baby. She did not seem to know the baby was dead. She remembered them arriving and she saw them on the floor with the baby – ‘kissing him and pushing his tummy’. She said that mummy said the baby got up and fell. She said the baby was crying before he fell on the floor. She did not see him fall.

The interview was conducted well and the interviewer resisted the temptation to ask leading questions. When asked ‘What did mummy do?’, the girl said, ‘Mummy was shouting on the phone that the baby fell down – come quick!’ She was asked ‘What did the baby do?’ – she replied, ‘He was crying too much. He was a naughty baby – mummy said …’.

Because the mother's account was not supported by the forensic findings in the baby and the evidence pointed to a shaking injury, the mother was charged and brought to trial. She pleaded not guilty. The explanation she gave was unlikely to be true as the baby was only 6 months old and therefore unlikely to have ‘got up’ of his own volition.

I had formed an opinion that the little girl was a competent witness and that at interview she was able to recall elements of the situation leading to and after the baby's death that could be helpful in determining what had occurred.

Before the jury was shown the child's evidence, the court heard the evidence of the Crown's expert pathologist, who was less certain, when challenged, of the significance of the post-mortem findings and the trial went no further. The doubt that his new evidence created was reason for the judge to direct the jury to acquit.