Killer who died after being tasered had psychosis 'brought on by drug use'
A prolific offender was experiencing a psychotic episode brought on by his cannabis and amphetamine use when he brutally killed and mutilated a "beautiful and caring" young woman, an inquest found.
The family of Cerys Yemm demanded reforms after recently-released ex-con Matthew Williams' horrific attack on the petite 22-year-old and questioned why agencies responsible for protecting the public from violent offenders could not have prevented the tragedy.
On Wednesday jurors ruled Williams, 34, who suffered a cardiac arrest shortly after being tasered four times by police officers, died a "sudden, unexpected" death caused through a "culmination of illicit drug use and struggle against restraint", following a three-and-a-half-week inquest into their deaths.
Miss Yemm's family said afterwards the killer should still have been in prison.
In a statement read by a lawyer they said: "We heard evidence that due to delays and errors in two criminal investigations, one of which included threats to kill, those prosecutions did not proceed and Williams was released from prison in October 2014 when he should have been in custody awaiting justice."
They called for " reform of the systems of monitoring and information sharing between agencies when offenders are released from prison" and said the relevant Welsh Government guidance on rehousing offenders was not followed.
"Even though Williams had said he wanted to make a fresh start out of the area, he was accommodated in an unsuitable B&B hostel in Argoed where he resumed his cycle of drug abuse," they added.
They also questioned whether "more timely" intervention by the police might have saved Miss Yemm's life that night and said they felt there was still a risk that offenders could be housed alongside vulnerable young people "without the local community having any idea of the risk they pose".
The jury at Gwent Coroner's Court, Newport, found Miss Yemm was unlawfully killed by Williams in his first floor room at the Sirhowy Arms Hotel in Argoed, South Wales, at around 1am on November 6 2014.
Williams used the broken shards of a cereal bowl to cut her face and neck, removed one of her eyes and bit her stomach, the inquest heard.
Miss Yemm's screams alerted other residents and hotel owner Mandy Miles opened the door to find the "horrific" scene of Williams, who had a history of drug use and mental health problems, on top of her with blood dripping from his mouth.
He carried on with his grisly attack despite the interruption, snarling "that is no girl" when asked what he was doing.
The jury found Williams, of Blackwood, " took amphetamine and cannabis which led him to experience drug-induced psychosis" and that h ad resulted in him becoming violent.
He had 26 previous convictions for 78 offences and had been released from HMP Parc, Bridgend, on October 23 2014 having served 27-months for blackmail.
The inquest heard that despite a previous diagnosis with schizophrenia he left with no medication after his mental health stabilised in custody.
He later met Miss Yemm, from Oakdale, on a night out and formed a "flirty" relationship with her.
After a weekend spent taking amphetamine and mephedrone, Williams spent the evening of November 5 with Miss Yemm at his friend's house where they drank lager and smoked cannabis, before going back to his first-floor room at the Sirhowy Arms at around midnight.
Miss Yemm suffered at least 89 individual injuries including at least three bite marks on her abdomen and her medical cause of death was ruled as sharp force trauma to the face and neck.
Williams was tasered three times after he had been arrested and placed in handcuffs and leg straps.
Dr Stephen Leadbeatter, who carried out the post-mortem on Williams, said he had been unable to determine a precise medical cause of death.
He gave a narrative cause of death that it was a "sudden unexpected death following a struggle against restraint (including discharge of a Taser) in a man with a history of schizophrenia who had taken amphetamine and cannabis".
The inquest heard Williams suffered cardiac arrest but the Taser use did not cause it and that he had a high concentration of amphetamine in his blood at the time of his death, as well as quantities of mephedrone and amphetamine of an unusually high purity level in his pocket.
The Independent Police Complaints Commission (IPCC), which investigated his death, said after the inquest officers acted with "reasonable and necessary force in traumatic circumstances".
Coroner David T Bowen told the jury he did not require them to make any findings of fact in relation to the wider circumstances, a decision which the Williams family said was regretful.
In a statement his family said evidence heard during the inquest had exposed "clear failings" in the mental health, housing and criminal justice system.
They said: "We hope that this case will highlight the need for better mental health care and lead to the effective sharing of information between state agencies and that another family will not have to go through what families touched by this inquest have had to endure."