But that approach changed when she returned to the Welsh capital in 2003 after being admitted to Whitchurch Hospital.

It was during this time that she was diagnosed with a borderline personality disorder and it was decided that there was no mental health intervention which could be offered.

Despite repeated contact with health and social services in the period leading up to Mrs Thomas’ killing, few risk assessments on Hancock were carried out.

Instead, the main focus was on her housing problems.

Hancock stabbed Mrs Thomas, 75, on October 19, 2005, in the Cardiff city centre Poundstretcher store.

A shop video of events showed Hancock enter the store, remove a knife from a shelf and open the plastic covering with a lighter.

Hancock is then seen approaching a woman, apparently with the intention of stabbing her.

She disappears from shot but when she returns another woman – Mrs Thomas – is seen with a knife handle sticking out of her back.

A joint statement from Cardiff Council, Cardiff Local Health Board and Cardiff and Vale NHS Trust said: “Although the report makes it clear that the homicide could not have been predicted, we acknowledge that Deborah Hancock received services that were less than optimal.

“We are working together to ensure improvements are made .

“Since this incident, specific changes in assessments, care planning and communication have been made.”