An NHS mental health trust has been slammed in a review into a number of killings by patients, including one who travelled to Scotland to attack his parents.

Artist Graeme Morris travelled almost 500 miles to his parents' home in South Ayrshire to carry out an attack on them as he wrongly believed they had harmed him as a child.

The 41-year-old began punching his father Fred, 64, after turning up at his bungalow in Troon on October 5, 2012.

His mother Anne, 63, suffered a fatal heart attack during the incident in Polo Gardens, while his father fled to a neighbour's house for help but was not initially recognised because he was covered in blood.

Morris, who was living in Brighton at the time of the attacks, was ordered by a judge to be detained indefinitely at the State Hospital in Carstairs at the High Court in Edinburgh.

Now, a review of ten killings, including Morris' case, has uncovered failings at Sussex Partnership NHS Foundation Trust.

The independent review has found the trust did not always learn fully from previous mistakes and sometimes "severely underestimated" the risk posed by mental health patients.

It also failed to include the views of families, some of whom pleaded for help, and did not always send people with signs of psychosis to specialist services.

Commissioned by the trust and NHS England, the review analysed previous reports into the ten killings to see if any lessons could be learned.

In two cases, experts concluded the deaths could have been prevented, although it did not say which ones.

The review found in seven of the killings there was criticism of how the the NHS trust assessed the risk posed by its patients.

In several cases, the process was reported to be "inadequate and the risk posed by the service user went unrecognised or was severely underestimated".

In some cases, "risks assessments were not completed or were completed incorrectly" and "risk management plans were not completed".

The review said "some diagnoses are incorrect and remained unchanged in the face of the service user's behaviour".

Former Glasgow School of Art student Morris admitted the culpable homicide of his mother and assault to danger of life of his father in 2013.

Morris had been diagnosed as suffering from paranoid schizophrenia and would pose a danger to the public if not treated in conditions of high security.

He was obsessed with the idea he was a genius and described as "strange and eccentric".

Morris also came to believe that, somehow, he had suffered as a child at his parents' hands.

Former girlfriend Emma Russell had been worried about his behaviour during the months leading up to the attack. She contacted a doctor and Morris was put on a waiting list to see a psychiatrist.

The court had previously heard Morris' parents were sitting in their conservatory when their son appeared and began to shout abuse.

He grabbed his mother, who was on a couch, by the hair before punching his father to the floor.

As Mrs Morris tried to struggle to her feet, her son slapped her face. Morris then continued battering his father as he lay on the ground, stripping him to his socks and kicking him.

Morris fled just before police arrived and took a train to Glasgow.

He confessed to hitting his parents but added: "I didn't murder my mother. I didn't have any intention of murdering either of my parents or killing them or for them to die."

Investigators looking at the Sussex trust found assessments were not updated when circumstances changed - such as a new criminal conviction - while some assessments were started but not completed.

"Sometimes service users made threats to kill others but no further action, for example informing the police or warning the person threatened, was taken," the report said.

Colm Donaghy, chief executive of Sussex Partnership, offered his "sincere apology and condolences" to families.

He added: "We commissioned this review with NHS England because we want to make sure we have done everything possible in response to these tragic incidents.

"We have a responsibility to the patients, families and local communities we serve to ensure this. "We have investigated each of the incidents individually. We also wanted independent, expert advice about any common themes which may link them.

"This review sends us a strong message about the need to identify and embed learning when things go wrong in a way that changes clinical practice and behaviour."