One hundred Sussex police officers and staff are now involved in the search for missing teacher Jane Longhurst.
With forces round the country assisting, Operation Keen is now one of the largest hunts launched by Brighton and Hove police in recent years.
House-to-house inquiries continued last night and police put up posters around the city appealing for information.
It is now 11 days since Miss Longhurst disappeared and detectives fear she has come to harm.
With no word from her and no confirmed sightings, her family and friends are beginning to fear the worse.
A geographic profiler from the National Crime Faculty has been called in to study photographs of the area where Miss Longhurst lives and to pinpoint areas police should search.
Officers have contacted other forces to check for links with other mysterious disappearances.
Miss Longhurst, 31, disappeared from her home in Shaftesbury Road, Brighton, on March 14.
Her distraught partner of four years, Malcolm Sentance, 34, kissed her goodbye as she lay in bed that morning and found her gone when he returned at 4pm.
He became increasingly worried as the evening wore on and called police at midnight.
Mr Sentance, an education welfare officer, has been out with his family searching the city streets.
He appealed to the public to "keep your eyes peeled for her".
He said: "I am living in limbo and hoping to hear good news."
Miss Longhurst, who teaches music at Uplands School for children with learning difficulties in Hollingdean, Brighton, vanished with just her black Next purse, flat keys and mobile phone.
Police said her credit cards had not been used and her phone appeared switched off.
Her family insist her disappearance is completely out of character.
Anyone with information should contact police on 0845 6070999.
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