A damning report into how a paranoid schizophrenic was released from a North Wales hospital and went on to behead a British grandmother in Tenerife seven months later is expected to be released today.
Homeless Bulgarian Deyan Deyanov, 30, launched a frenzied knife attack on 60-year-old Jennifer Mills-Westley while she was shopping in the popular resort of Los Cristianos in the Canary Islands, Spain, on May 13 2011.
The drug addict was sentenced last February to 20 years in a secure psychiatric unit after he was convicted of murder by a jury.
Deyanov was admitted to the psychiatric unit at Glan Clwyd Hospital, Bodelwyddan, near Rhyl, in 2010 while he stayed at an aunt's home in Flint but was released in October that year.
Healthcare Inspectorate Wales (HIW) was commissioned by the Welsh Government to carry out an independent report into the care of Deyanov after Ms Mills-Westley's two daughters pressed for an inquiry.
Betsi Cadwaladr University Health Board, which runs Glan Clwyd, carried out its own internal review which concluded lessons had been learnt but said it would co-operate with the HIW probe.
Julian Hendy, director of charity Hundred Families - which supports loved ones of those killed by people with mental illnesses - said: "We understand the report from Healthcare Inspectorate Wales is likely to be damning in its assessment of the care Deyan Deyanov received in North Wales, just months before the dreadful killing of Jennifer Mills-Westley.
"There have been previous investigations into the care of mental health patients in North Wales who have gone on to kill and I understand it's likely that very similar failings will be documented in the Deyanov Investigation.
"Our charity has studied very many of these health service investigations throughout the country and what troubles us is the failure of mental health agencies to learn lessons effectively from these tragedies - so that avoidable deaths keep on occurring and innocent people are losing their lives unnecessarily."
On the morning of the murder, in a Chinese-owned general store near the beach, Deyanov picked up a 22cm-long knife and plunged it repeatedly into Ms Mills-Westley's neck.
He then walked out carrying her head, to the horror of onlookers, before being wrestled to the ground and arrested.
Ms Mills-Westley, a retired road safety worker originally from Norwich, had complained that Tenerife was less safe than when she started visiting 30 years ago.
Deyanov was well-known to police on the island and had been arrested at least four times since January 2011 for violent offences.
He was sectioned at Tenerife's La Candelaria hospital before being bailed in early February 2011.
A warrant for his arrest was issued three days before the killing but officers were unable to locate him.
After Deyanov's trial, Sarah Mills-Westley, from Norwich, and sister Samantha, who lives in the Midi-Pyrenees region of France, said a "catalogue of failings" by "a number of authorities" led to their mother's death.