Another offender is on the run from Ford prison.
Peter Mahoney did not return from day release on Friday, when is thought to have travelled to Brighton.
Police say the 37-year-old’s disappearance is a “concern”, given his history of violence.
He was jailed indefinitely for a minimum four years in 2010 after admitting violent offences from 2008.
He shot a shop customer with an air pistol in south London on November 5 2008, and the next day stole a car from a group of friends near Dartford. He told them he was a police officer before threatening them with an airgun.
PC Steve Reed said: “Mahoney has a history of violence and is therefore a concern. We need to recapture him as quickly as possible.
“We need people to contact us if they see him or know where he is. If you see him, do not approach him but call 999 immediately instead.”
Mahoney, 37, is white, 6ft 2in and of average build. He has links to London and Kent.
In June Sussex police said 89 offenders were missing from the prison, near Arundel. Superintendent Lawrence Hobbs said the force was “prioritising efforts to trace and arrest them”.
Anyone with information about Mahoney should call 101, email email@example.com or call Crimestoppers anonymously on 0800 555111.
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