It has been like this for the past 55 days. Ever since an unknown assassin - probably a well dressed man in his late 30s or early 40s - stepped up behind the television presenter Jill Dando and shot her dead, the lives of these murder squad detectives have revolved around nothing else.
Yesterday The Independent was given exclusive access to take photographs in the murder incident room in Earls Court, west London.
A dozen officers were busy with their heads down, sorting through statements, answering phones or else adding more documents to the already bulging files.
On the office walls were various pager and mobile phone numbers for the senior officers, while on a large notice board at the front of the room, someone had written in black marker pen the pertinent details of Operation Oxborough.
In the past few weeks, attention has focused on how slow the investigation has been. After the initial flurry of the first few days - the release of the description of the well-dressed suspect running from the scene, the e-fit of the man sweating at the bus stop and the emotional appeal from Ms Dando's fiance, there has seemingly been nothing.
There has been mounting speculation that the murder of Miss Dando - a crime so extraordinary that many people could barely believe their ears when they first heard the news - may be one of the 10 per cent or so of murders that is never solved.
But yesterday the detectives working on the case were in a genuinely optimistic mood.
"It's quite simple. Everyone is determined to find whoever did this. We have to keep morale up so it is no good coming in every day thinking `Oh we're never going to get this person'," said a senior detective involved in the investigation.
"We believe we are going to find this person. We realise we are not going to find them tomorrow - it's going to be a long haul - but we are confident.
"It's like any job you do - if you are going to do it, you want to do it properly. And we are the same as everybody else; everybody wants to know who killed Jill Dando."
Since Ms Dando, 37, was shot dead with a single bullet to her head as she stood on the doorstep of her home in Fulham, west London on 26 April, the incident room has received and dealt with more than five thousand telephone calls, letters and faxes from members of the public about the killing.
Some have contained potentially vital information. It was from the public that police were able to draw up the description of both the suspect and the man seen later at the bus stop.
It was also from members of the public that police were able to put out the description of the metallic blue Land Rover seen racing through neighbouring streets being driven by someone who may or may not have been an accomplice. It was the public too, who later reported seeing a man - possibly the suspect - sweating heavily as he got on a bus.
Of course much of the information is useless - some of it phoned in by drunks in the early hours who leave slurred messages on the incident room telephone answering machine. And then there are the countless calls from people who wish to ring in and recount their own pet theory on the case, explaining how Ms Dando was killed by Serb gunmen, a senior politician, underworld gangsters or aliens.
"We have had more theories than you could imagine," said another detective who is based in the incident room on a daily basis.
"If we listed the names of everybody who has been named to us as the killer I think we would have a third of the population of Britain."
But in many ways theories are all the police appear to have. There are 42 detectives still working on the murder and the incident room is staffed seven days a week, but they are desperate for a breakthrough.
They have seized thousands of hours of security film from the four London airports - Heathrow, Gatwick, Luton and Stansted - which may be examined later to see if the killer fled the country. They have taken 700 witness statements from people in the area without finding anyone who saw the man running from the scene well enough to produce an e-fit. (The e-fit they did release is of a man seen later at a bus-stop. Police are not convinced it is the same person.)
They have also made painstaking inquiries into Ms Dando's private life, going though her private contacts book, speaking to her colleagues and interviewing anyone who knew her.
They have even analysed thousands of mobile phone calls made in Fulham at the time of the murder - assisted by the Government's secret listening centre GCHQ at Cheltenham - to see if they can trace the call that the suspect was seen to make as he left the scene of the murder.
They have done all of this and still, frustratingly, they have come up with nothing tangible.
"I think we all know that if we can can answer the question `why?' we will answer the question of who," said one officer.
But without that, the detectives are forced to manage with the little they do have. They have a bullet and cartridge used in the murder which came from a "short" 9mm handgun, probably a Walther PPK or Browning; they have the aforementioned description of the suspect and - perhaps something often overlooked - they have a great deal of public goodwill,
"It's absolutely awful," said Maria Lumley, one of Ms Dando's neighbours, earlier this week, summing up the feeling of most who knew her.
"She was a lovely person and she fitted in so well in the neighbourhood."
And for what it is worth they also have the support and backing of the person who probably knew Ms Dando better than anyone, her brother Nigel, chief reporter with the Bristol Evening Post.
"I do remain optimistic. It may not be sooner rather than later but we are prepared for it to take a long time," Mr Dando said.
"The police are still getting lots of information from the public. We are sure that somewhere in all of this information there will be the vital clue that will lead to the killer or the killers being caught. I am sure they will solve the crime. It is what is keeping us going."
profile of an inquiry
Team of 42 officers working on investigation. Inquiry office staffed seven days a week, 24 hours a day.
More than 5,000 telephone calls, letters and faxes from the public. 500 calls followed Crimewatch programme.
700 witness statements taken.
"Thousands of hours" of surveillance film examined from shopping centre and road cameras.
Security film seized from the four airports at Luton, Gatwick, Heathrow, and Stansted.
Thousands of mobile telephone calls made in Fulham area traced.
The suspects and the Theories
SUSPECT: Serbian hitman
THEORY: Serb hitman, possibly a soldier, carries out execution as a reprisal for Nato bombing of Serb television station which killed a number of presenters and technicians. She became a target after fronting televised Kosovo appeal.
PLAUSIBILITY: Ms Dando's publicity office had received rambling threat letters from people claiming to be Serbian following her television appearance.
POLICE VIEW: Sceptical, although it was not ruled out when first mooted. Considered highly unlikely.
SUSPECT: Criminal jailed as a result of BBCTV's Crimewatch programme
THEORY: Underworld hitman hired by vengeful criminal who has been convicted as a result of information gleaned by Crimewatch presented by Ms Dando.
PLAUSIBILITY: Killing bore many hallmarks of a professional hit except that the killer made no attempt to conceal identity.
POLICE VIEW: A real possibility, but extremely hard to narrow down because so many suspects. Given extra credibility because it offers an explanation for the professional way in which murder was carried out.
SUSPECT: A stalker
THEORY: An obsessive fan, jealous at recent publicity surrounding forthcoming marriage, decides to punish Ms Dando or loses control during confrontation.
PLAUSIBILITY: Stalkers rarely physically harm the object of their obsession and acquiring an untraceable pistol would be beyond the means of most people without serious connections to the criminal underworld.
POLICE VIEW: Considered at first to be the most likely explanation, although lack of evidence that Ms Dando was being stalked has made it less likely.
SUSPECT: Fiance Alan Farthing
THEORY: Private dispute, possibly over previous relationships, leads the gynaecologist to murder his bride-to-be
PLAUSIBILITY: Most murder victims are killed by people they know but Dr Farthing was working at the time of her death.
POLICE VIEW: One of the more obvious explanations in any murder, but inquiries have completely ruled out Dr Farthing as a suspect.
SUSPECT: Figure from her private life.
THEORY: A person from her private life jealous at her success or angry over her forthcoming marriage, hires professional assassin.
PLAUSIBILITY: Family, colleagues and friends say there are no skeletons in her cupboard. Ms Dando, a committed Christian, well-liked and known for charity work and a media career built without duplicity.
POLICE VIEW: Very likely, but intensive inquires have found no strong suspects. Investigations are continuing, although whoever was involved almost certainly needed criminal or military contacts to have carried out the killing.
SUSPECT: A mugger
THEORY: An opportunist robbery attempt ends in a fatal shooting when Ms Dando tries to resist.
PLAUSIBILITY: A recent spate of high-profile celebrity muggings raised the possibility that she was mugged. But the would-be mugger did not steal anything of value from the crime scene.
POLICE VIEW: Very unlikely. Muggers do not clinically shoot dead their victims and leave behind the valuables.
SUSPECT: Disgruntled patient of Alan Farthing
THEORY: A patient who failed to sue Dr Farthing or was infatuated with him gets revenge by hiring a contract killer.
PLAUSIBILITY: Passion and revenge are common motives.
POLICE VIEW: Initially believed to be a real possibility, but now ruled out.