A convicted killer dubbed the Black Dog Strangler has escaped from a secure hospital, police said tonight.
Phillip Westwater, 44, fled St Nicholas Hospital in Gosforth, Newcastle, at 10am after asking to go to the toilet.
He was detained indefinitely under the Mental Health Act following a pub fight in 1989, then strangled fellow patient Derek Williams at Ashworth Hospital, Liverpool, with his dressing gown cord.
He admitted manslaughter on the grounds of diminished responsibility, having become convinced his victim had turned into a black dog.
Northumbria Police said the public should not approach Westwater.
A spokesman said: "Officers are making inquiries into this individual and any risks he may or may not pose.
"In the meantime people are asked to contact police on the 999 emergency number if they see him and not to approach him."
The police spokesman added: "At 10am on January 2, Mr Westwater was being escorted in the hospital when he asked to go to the toilets, from where he escaped."
Westwater is described as white, 6ft and of slim build, with brown/grey hair.
He left his clothes in the toilet so police have no description of what he is wearing.
Westwater, from Newcastle, married a nurse while he was a patient at high- security Rampton Hospital in 2008.
He and his bride, reported to be Claire Dudley, wed in a social club at the Nottinghamshire hospital.
Nottinghamshire Healthcare NHS Trust said the right to marry was enshrined in the 1988 Human Rights Act.
A hospital spokeswoman denied the couple could consummate their marriage while he was being treated there.
In 1989 Westwater left a drinker paralysed for life after slashing him across the throat with a shard of glass in a pub fight. He killed Williams at Ashworth Hospital the following year.
Before being treated at Rampton, Westwater had also been a patient at Broadmoor.
St Nicholas Hospital in Newcastle is considered a medium- security unit.