A man who was given three life sentences for trying to kill a shopkeeper is missing from prison.
Anthony Bolden was last seen at HMP Spring Hill in Buckinghamshire on 30 May.
Bolden was on licence from another jail term when he stabbed a shopkeeper 18 times and swung a shovel at a police officer in 2005.
Thames Valley Police said the 55-year-old has tattoos on his arms, torso and left hand.
He is described as white, 6ft 1in (185cm) tall, of slim build with short grey hair.
Det Sgt Bruce Wilson warned the public not to approach Bolden but to call police on 101 if they saw him.
Bolden is believed to have links to Hoddesdon in Hertfordshire, Woodbridge in Suffolk, March in Cambridgeshire as well as Kingston-Upon-Thames and West Kensington in London.
In 2006, Bolden pleaded guilty to attempted murder, attempting to cause grievous bodily harm and robbery.
He was sentenced to three life sentences and ordered to serve a minimum term of at least seven-and-a-half years.
Sentencing him at the time, Judge Jeremy Roberts described Bolden as a very considerable danger to the public.
HMP Spring Hill is a Category D open prison with a capacity of 335 inmates.