Shannon Matthews unit to help search for missing office worker

A taskforce from the National Policing Improvement Agency (NPIA) also helped snare Ipswich murderer Steve Wright and were involved in the Madeleine McCann case

Ms Pilley, 38, set off for work on Tuesday 4 May but never arrived.

The NPIA's involvement comes after Lothian and Borders Police said they had "grave concerns" for Ms Pilley's safety.

The agency, which supports high-profile investigations across the UK, will provide access to specialist equipment and techniques.

Iain Livingstone, Assistant Chief Constable of Lothian and Borders Police, said this type of investigation was rare and described the NPIA's support as "invaluable".

He said: "We have grave concerns for Suzanne's safety, and we cannot rule out the possibility of a criminal act.

"The dedication of all officers assigned to this inquiry is commendable, with a high volume of work already completed, and a vast number of investigative avenues explored.

"In saying that, however, any inquiry can only benefit from the expertise of advisers from around the country."

Friends of Ms Pilley have set up a Facebook page to help in the search, which members of the social networking site can access by searching for her name.

Earlier efforts to trace Ms Pilley included a huge screen positioned in St Andrew Square, which displayed CCTV footage showing her on the way to her office.

On the day she went missing, Ms Pilley boarded the No 2 bus at Stevenson Drive at 8:20am, getting off at 8:32am and then changing to the No 4 bus at Dalry Road, opposite Caledonian Terrace.

She got off the bus at Jenners in Princes Street at 8:48am then went into the Sainsbury's supermarket near St Andrew Square.

Ms Pilley was then recorded on CCTV footage outside Sainsbury's at 8:51am. Finally, at 8:55am, she was captured on CCTV next to a people carrier taxi at the junction of North St David Street and Thistle Street – just 50 yards from the front door of her workplace, with financial services firm Infrastructure Managers Ltd.

A spokeswoman from Lothian and Borders Police said enlisting the help of the NPIA would boost the investigation.

"They hold a huge wealth of expertise. Thankfully this type of case is so rare that individual forces might not have that much experience so to have a team of experts will be a great help."

She added: "Some of them will be based within Lothian and Borders Police stations and others helping will be based elsewhere in the UK."

In 2008, the NPIA took over the operation of the national Missing Persons Bureau from London's Metropolitan Police.

A spokesman for the NPIA said: "We are sending up a team who have worked on major missing persons inquiries. They have a range of specialist skills, knowledge and techniques."

Ms Pilley, from the Stenhouse area of the city, is described as being white, 5ft 4ins tall, of slim build with short, light brown hair shaped into a bob.

Detective Chief Inspector Gary Flannigan, who is leading the inquiry, said: "We are still keen to hear from people who may have seen Suzanne since her last sighting on North St David Street."