It has been exactly a month since 14-year-old Alice Gross failed to return home to her family, sparking the Metropolitan Police's biggest search operation since the 7/7 bombings.
More than 300 officers from over a dozen police forces across the country are involved in the increasingly desperate hunt, which this weekend called on the assistance of the RAF who helped to identify possible new search sites.
Yellow ribbons adorn homes and railings in west London where the community have been praised by officers for their help in raising the profile of the missing teenager.
Today hundreds of the ribbons were handed to runners at the Ealing Half Marathon in a bid to spread the word.
Alice was last captured on CCTV walking along the towpath next to the Grand Union Canal as it passes under Trumpers Way at 4.26pm on August 28 but has not been seen since.
Detectives are scouring through hours of "crucial" footage from hundreds of CCTV cameras for clues in piecing together her last movements, while officers continue to comb through scrubland running alongside the canal.
Convicted murderer Arnis Zalkalns, who was filmed cycling the same route behind the teenager remains the prime suspect in her disappearance.
Police are urgently working with the authorities in his native Latvia to track down the labourer who was reported missing within days of Alice's disappearance.
A Metropolitan Police spokesman said it continues to be a "massive investigation".
Speaking of the latest developments, he said: "We can confirm that as part of the search operation, the RAF has provided assistance in the form of aerial analysis to identify potential areas of interest to officers.
"A range of officers and staff from across the Met are taking part in the ever-expanding search for Alice.
"To date the search has involved the Met's underwater and confined space search team, marine support unit, search dogs, air support unit, Territorial Support Group, local borough officers, volunteer police cadets, visual images identification and detections officers, plus licensed search officers."
The Ministry of Defence confirmed the RAF was helping police in the search for Alice.
A spokesman said: "We can confirm that the MoD is providing routine support."
The search has also included a reconstruction of Alice's last known movements which attracted 150 phone calls from members of the public with possible information.
But an area of disturbed earth at Elthorne Park in west London, which runs beside the canal towpat h and was subject to a thorough investigation, was ruled out as no longer of interest.
Her mother, Rosalind Hodgkiss, said: "Every morning, as Alice's disappearance grows longer and longer, brings new agony, new anguish."
The force has come under fire for delays in identifying Zalkalns as a risk, and Commander Graham McNulty admitted that British detectives would have no power to arrest him if he has fled abroad.
The general labourer, who worked at a building site in Isleworth, west London, is thought to have come to the UK in 2007, but authorities here have come under fire for apparently holding no record of his conviction for bludgeoning and stabbing his wife Rudite to death in Latvia.
He is described as white, 5ft 10in and of stocky build, with dark brown hair that he normally wears tied in a ponytail.