30/03/2016 22:37 BST | Updated 31/03/2016 12:00 BST

Cerys Yemm: 'Cannibal Killer' Matthew Williams Had Taken Drugs Since Age Nine, Report Finds

Inquest into Yemm's death expected later this year

A killer who murdered a woman and then chewed on her face was driven psychotic by drugs, a review has found. 

Matthew Williams murdered Cerys Yemm, 22, at the Sirhowy Arms in Bargoed, south Wales, in November 2014, just two weeks after being released from prison. 

The 34-year-old, who had been serving a jail term for attacking an ex-partner, died after being tasered by police at the scene. 

Cerys killer Matthew Williams used drugs since age nine, a report has found

Healthcare Inspectorate Wales has now revealed that Williams had been a drug user since the age of nine, the Mirror reported. 

It said Williams was likely to have had a severe reaction to "psychoactive substances" he took, and that he had been offered help to address his addiction but had declined it.

Yemm was killed at the Sirhowy Arms in Bargoed, south Wales, in November 2014

However, the report concluded it was "difficult" to see how the tragedy could have been predicted or prevented by health services.

A post mortem examination on Yemm recorded a provisional cause of death as sharp force trauma to the face and neck.

An inquest into the shop worker's death is expected to take place later this year.