Malcolm Millman has links to Canterbury in Kent
A man absconded from a medium security unit while on a day trip to a Buddhist monastery, police have said.
Malcolm Millman, 58, who was being held at Chadwick Lodge in Milton Keynes, disappeared during a visit to St Margaret's in Great Gaddesden, Hemel Hempstead, at 14:00 BST on Saturday.
Convicted of rape in 1996, Thames Valley police said he is "a potential risk to the public".
He was last seen on CCTV at Manchester Airport on Monday.
However, Supt Olly Wright said officers did not believe Millman had access to a passport.
He warned the public not to approach Millman, but instead ring 999 if they see him.
"Based on Millman's previous convictions, including rape, we believe he is a potential risk to the public," he said.
Walking stick
Millman is believed to have travelled from Hemel Hempstead to London on Saturday and then taken a train to Leeds.
Officers now believe he may have taken a train or bus from Manchester Airport.
Millman is described as white, of large build, bald with thinning brown hair on the sides and brown eyes.
He was last seen wearing a brown jacket, purple jumper, grey tracksuit bottoms, blue and white trainers and carrying a walking stick.
Also known by the names Richard Simon Barber, Michael Geoffrey Newman and Raymond Pilkington, he has links to Kent.
Chadwick Lodge in Eagleston is a secure unit which provides specialist treatment programmes for male and female patients who have been detained under the Mental Health Act (1983) and have a history of offending.
