Police have been searching a lake in an effort to find a "vulnerable" man who was last seen at a hospital.
Norfolk Police said the last known sighting of James Whitman, 40, was at the Norfolk and Norwich Hospital at around 4pm on Monday.
Teams have spent the day searching the lake at the University of East Anglia.
Police officers, volunteers from lowland search and rescue, and the police dog and drone units have also spent the week searching for him in the Eaton, Bowthorpe, Cringleford and Earlham Park areas of Norwich.
Police said they believe Mr Whitman may have been in Earlham Park, near the University of East Anglia, after leaving the hospital on Monday afternoon.
"We’ve been looking for James for the past three days [...] and I’m sorry to say that, unfortunately, there isn’t any sign of him," Insp Adam Binns said.
“This, combined with the results of our enquiries, suggests something may have happened to him. Today our focus turns to searching the lake at the UEA.”
Mr Whitman is described as white, 5ft 10ins tall, with short blonde hair which is thinning on top.
The last known picture of James Whitman was released by the force on Wednesday.
It shows him wearing a navy-blue polo top with the letter A on his chest, navy-blue trousers, and blue and white trainers.
Anyone with information is being urged to contact Norfolk Police on 101 quoting incident number 341 of Monday 13 June.
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