Transsexual Helen Doe, 53, outside Kingston Crown Court. She is accused of attempting to murder her brother but denies the charge against her

A transsexual police worker who told police she wanted to kill her brother after beating him over the head with an iron bar while he slept has now claimed she was sleep walking at her trial for attempted murder.

Helen Doe, 53, allegedly beat Kenneth Doe, 64, with a foot-and-a-half long metal pole after she woke up with an 'overwhelming' sense of hatred towards him.

Mr Doe was left with his head covered in blood and suffered severe lacerations and a fractured finger after the attack in their shared house in Mitcham, Surrey, on July 5 last year.

But today Kingston Crown Court heard that a combination of medication for depression and hormone treatment may have caused Doe to sleepwalk and attack her brother.

Miss Doe, who works for the Metropolitan Police Uniform Services and is a vocal transphobia campaigner, is pleading not guilty to attempted murder, despite telling police she wanted to kill him after the attack.

Paul Cavin, prosecuting, explained how Miss Doe called the police shortly before 4am and said words to the effect of 'I have had an accident, I think I have killed my brother'.

She told the operator she had hit him with an iron bar, then said 'I've been building up to it'.

When the police arrived, she admitted to the attack immediately and police found an iron bar on the table, covered in blood, explained Mr Cavin.

Mr Doe told police: 'I had an argument with her earlier and I woke up and she was hitting me with an iron bar. I don't like her friends.'

Miss Doe was cautioned at the scene and asked the officer 'can I have a cuddle' as her brother, who was still conscious, was taken to St George Hospital for head injuries and a fractured finger.

Mr Cavin said: 'She began to cry and asked the police officer whether she was going to a mental hospital.

He added that she then spoke freely to officers in the van after the incident, saying 'I don't want to hurt anyone,' but later adding, 'I wanted to do it, I wanted to kill him.'

Mr Cavin said: 'She said her friendship with her brother was not a good one and woke in the early hours with an overwhelming hatred of her brother and she makes reference to muffled voices in her head.

He added: 'Fortunately he didn't die, and fortunately he suffered no long term injuries at all.

'However, it is the prosecution's case that in striking him several times that, simply, she intended to kill him.

Miss Doe's trial continues at Kingston Magistrates Court. She claims that a combination of drugs for depression and hormone treatment led her to sleepwalk and commit the violent act

'It may be that she was not strong enough, it may be that her brother parried or blocked some of the blows.

'But the prosecution say that evidence will clearly show that she intended that death would result.'

Jurors were told that Doe was suffering from a history of depression at the time, for which she was taking medication, while she was also undergoing hormone therapy for a sex change.

Mr Cavin warned jurors that the defence may suggest that a combination of the drugs for her depression and her hormone therapy may have caused Doe to attack her brother.

He suggested the defence would argue that the drugs had caused non-insane automatism, also known as involuntarily movement of the body, limbs or person.

'The actual events may not be in any dispute at all,' Mr Cavin said.

'The defence will suggest that the expert evidence points to the conclusion that Ms Doe was sleep walking when she attacked her brother, and the fact that she was sleep walking and became violent was because of some of the drugs she was taking.'

Doe is a prominent member of Croydon's transsexual community who was one of the driving forces behind the Croydon Trans Group and began living her life as a woman in 2009.