Man held indefinitely for fatal attack on sister

A man has been detained indefinitely under a hospital order after stabbing his sister 40 times under in what her family described as a "totally avoidable" killing in south London.

Andrew Cunningham, 62, attacked mother-of-three Margaret O'Brien, 57, as she visited their mother in Rotherhithe on 29 November 2024.

Cunningham admitted manslaughter by diminished responsibility due to his history of drug-induced psychosis and had tried to seek medical help hours before the killing.

The Old Bailey heard how Cunningham had displayed "anger and rage" towards his family and had threatened to "kill the lot of you" in the past.

In a victim statement, O'Brien's youngest sister Linda said the killing was not a "momentary lapse" but the culmination of a lifetime of anger, jealousy, intimidation and resentment which ultimately cost her sister's life.

For the prosecution, Nneka Akudolu KC told the court the defendant had lived alone with his mother, Margaret Cunningham senior, in Greenland Quay and been her carer since the death of his father in 2022.

His family had repeatedly raised concerns with his GP about his mental state, and the defendant had himself contacted the surgery 10 times in October and November 2024.

Cunningham was suffering a severe depressive episode with psychotic symptoms and had called the surgery hours before the killing asking to see a doctor saying "I feel terrible, like in my head".

He was advised to fill out and online form and attend the surgery if he needed any help completing it, but never made the appointment.

At 14:30 GMT on 29 November 2024, police were called to the home following reports that a woman has been seen screaming for help covered in blood from a first floor window.

Cunningham had also called the police himself saying "I've stabbed my sister."

The victim died later that evening in hospital.

Around 40 minutes after leaving the scene, Cunningham threw himself into the River Thames but was found standing in chest-deep water holding a life-ring.

He told police he had stabbed his sister due to being under stress after looking after his mother for the last two years.

However, in a non-molestation order application six months before her death, O'Brien described her brother as a "very violent individual" who was "capable of causing me pain by verbally, physically and emotionally abusing me".

The court was told Cunningham had 21 previous convictions for 31 offences including assault, burglary and an armed robbery when he was aged 19.

In a victim impact statement, widower Anthony O'Brien said: "This tragic event was so avoidable and unnecessary.

"No sentence can possibly replace the loving, kind, warm and funny person we have lost."

O'Brien's youngest sister Linda said: There is no justification. There is no forgiveness for the choice he made to end our sister's life. The impact of this crime is permanent. We will carry this pain, trauma and loss for the rest of our lives.

"Explaining behaviour is not the same as excusing it. Accountability matters. Margie's suffering matters. Margie's life matters."

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