"Very naughty"

"Well, that was a very naughty thing to do, wasn't it, to think of killing little boys and girls and talk about it?"
Prosecution question to Norma Bell
On 17 December 1968, at Court Two at the Newcastle Assizes, the court is told that the two defendants in the dock murdered "solely for the pleasure and excitement of killing". In an effort to make allowance for the young age of the defendants, Mr Justice Cusack rules that lawyers can sit with their clients.
Over the course of nine days, the court hears testimony from both Mary and Norma. Prosecutor, Rudolph Lyons opens the trial suggesting that whoever murdered Brian also murdered Martin.
The court hears of the evidence from handwriting experts about the confessional notes found at the nursery, which are linked to both girls. It is told of the morbid questioning of the victims’ families by Mary, and how she had asked to see the dead bodies. Forensic evidence implicates Mary as gray fibres from one of her wool dresses were discovered on the bodies of both victims. Fibres from Norma's maroon skirt were found on Brian's shoes. Taken all together it makes for a strong case against both defendants.

As with their police interviews, the sharp contrast between the two girls plays out in court, particularly when they take the stand to answer the barristers’ questions. Mary maintains her intelligent, dominating manner; giving witty quips to the lawyers. Observers call Norma a "pathetic child who is overwhelmed by trial".
After the children's testimony, the defence calls the psychiatrists who’ve examined Mary. Dr Robert Orton testifies that she suffers from a psycopathic personality disorder, that she has a demonstrated a lack of feeling towards others and is liable to act on impulse.
The jury of five women and seven men take under four hours to return a verdict. Norma is found not guilty of manslaughter, as she is considered to be “simple minded”. Mary Bell is cleared of murder but found guilty of the lesser charge of manslaughter. The judge passes a sentence of detention for life.
Mr Justice Cusack, describes Mary as dangerous and posing a "very grave risk to other children". Mary’s psychiatrists rely on observations alone; no-one comes forward from her family to try and explain how her past may have affected her behaviour.