James Manley, 48, was last seen in Victoria Park in east London E3, at 11:15 this morning.
Scotland Yard have revealed Manley was convicted of a robbery two years ago and was subsequently detained under the Mental Health Act.
Anybody who has spotted James Manley is urged to contact the police.
Image: Metropolitan Police
He is believed to have travelled through Waterloo Station this afternoon.
He is described as a male of large build, bald with lots of scars on his head.
He was last seen wearing a black jacket, white trainers, grey shorts, black t-shirt and glasses
Police are advising the public not to approach him and, if the see the suspect, they should call 999 immediately.
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