It has been eight days since a gang of thieves hoisted a £3m Henry Moore bronze sculpture on to a flatbed lorry and then made off into the night.
Since then nothing has been seen of the two-tonReclining Figure, apart from a handful of sightings an hour after the theft from a sculpture park in Hertfordshire.
But as the days go by without the recovery of one of Moore's most famous works of art, police are increasingly expecting a telephone call from the thieves trying to claim the £100,000 reward.
Another possibility, believes the detective heading the Moore investigation - codenamed Operation Soufflé - is that the gang had the bronze melted down within 48 hours of the raid and sold it for a few thousand pounds. The police have so far searched two scrapyards in east London and are continuing to investigate one of them.
The theft at 10.10pm on 15 December from the Henry Moore Foundation in Perry Green has made worldwide news and baffled art and crime experts.
Detective Chief Inspector Mark Ross, who is heading the 25-strong team from Hertfordshire Police, said yesterday: "We are still open-minded about the motive, but we think it is most likely that someone either stole it for scrap not knowing its value, or someone is keeping it and hopes to get a reward.
"We are leaning towards the possibility that someone will give us a ring, saying, 'We want the reward'."
The police have not discounted the possibility that the bronze will be shipped overseas and an alert has gone out to all ports as well as to Interpol in case it is offered for sale abroad.
Det Ch Insp Ross said that the sculpture had been left in a courtyard for several weeks before it was stolen and that the area, set in a wealthy stockbroker belt, was popular among travelling criminals looking for something to steal.
"There are certain people who travel around the area looking for cars, or lumps of metal to steal and sell for scrap," he explained.
The theft was not reported to the police until 17 hours after the sculpture was snatched, giving the three-man gang plenty of time to hide it, or have it melted down.
Officers carrying out the investigation have been given names of several suspects from anonymous tip-offs, but so far no one has been arrested. Police are also examining film from surveillance cameras that caught the lorry with the stolen Moore sculpture in Harlow, Essex, about an hour after the raid.
Last Sunday the Mercedes flat-bed lorry which was used to steal the three metres-long sculpture, was found abandoned in Coopersale, near Epping, in Essex.
The lorry, with a lifting crane on the back, had been stolen from an address in Roydon, Essex, about an hour before the theft. So far no forensic material, such as DNA, has been recovered from the vehicle.
Everyone is agreed that the theft was a well-organised and professional "job", which took less than 10 minutes to carry out.
It is for this reason that some specialists believe the gang had more ambitious plans than selling it for an estimated £5,000 scrap.
Dick Ellis, former head of Scotland Yard's arts and antiques squad and director of the Art Management Group, an art security firm, said: "If you look at how they stole it there was a great deal of planning. It was too carefully worked out to just end up with scrap.
"I would store it in a container park and wait for all the fuss to die down. This could be months or even years.
"Maybe the thieves have already found a buyer, or maybe they will need to look for one. It could have already left the country. One possibility would be to somewhere like the former Eastern bloc."
Mr Ellis, who led the police team that recovered Edvard Munch's The Scream three months after it was stolen in Oslo in 1994, also dismissed the idea that it had been stolen to order by a crooked art collector.
Charles Joint, head of finance at the Henry Moore Foundation, described the sculpture - which is one of seven casts - as an important work of art. " It will be sorely missed, although we are still hopeful of getting it back," he said.
On the issue of security at the park, Mr Joint said there had to be a balance between openness and protecting the artwork. "We could always put up a wall, lock the gates, and deny anyone access," he said.
"Until now we have considered the measures we have taken were sufficient, but this is clearly not the case. We are introducing tighter measures."
Small is beautiful - particularly to a thief
Thieves have always been interested in Henry Moore's works, but until now they have concentrated on his smaller items - in particular, his collection of 3,000 drawings and 8,000 prints. These are easy to slip into a pocket or bag and as well as being convenient to steal, they can fetch thousands of pounds at auction.
Similarly, criminals have gone for his maquettes - preliminary models - and small-scale sculptures. The added advantage of stealing the smaller pieces is that they are often casts, with potentially dozens of similar copies, and this makes it far harder for stolen items to be recognised at auction.
In 1997, a 10-inch sculpture worth £52,000 was stolen from the Waddington Gallery in London. It was subsequently found in a London taxi during a routine security check.
Two years before, his King and Queen sculpture was "beheaded" at its site overlooking the Glenkiln reservoir near Dumfries. The missing head was later recovered.
Alexandra Smith, sales director of Swift-find Limited, which has an online register of 335,000 stolen items that includes arts and antiques, said: "Until now no-one really expected thieves to use a truck to run off with a two-ton sculpture. Thefts of Henry Moores have tended to be items that can be easily hidden."
She added that while there are dozens of stolen Henry Moore sculptures and drawings in circulation, thieves' most popular artist - largely because he was so prolific - is probably Pablo Picasso.Reuse content