In the briefing room on the first floor of Chadderton Police Station, Lancashire, Andy Tattersall addresses his murder squad. The team of 23 sits patiently as "Tat" works through each of the open cases.
"Is that expert witness going to testify?" he asks. "Have we got the forensic results back on the murder weapon in your case?" he demands.
Finally, with a look of grave concern, he asks no-one in particular: "Who is sorting out the Christmas party?"
It is a scene replicated across Britain's murder investigation teams every morning, but the difference with Mr Tattersall's team is that it has no detectives: the entire squad is staffed by civilians.
The Category C Unit is Britain's first, and so far only, murder squad staffed purely by civilian investigators – unwarranted members of police staff with no powers of arrest.
One of eight murder teams in Greater Manchester Police, the unit, as its name suggests, investigates only category C murders, the lowest-level murder cases where alleged offenders may be known to the police.
It has been operational for less than two years, in that time dealing with 33 murders and leading to charges pressed in 28 of them, a detection rate of 85 per cent – higher than the overall Manchester Police rate of 77 per cent.
Some of those cases have been high-profile. Cat C Unit handled the case of Jael Mullings, the 22-year-old mother who fatally stabbed her two infant sons.
And it is currently preparing the case against Martin Forshaw, 26, the police officer accused of murdering his 31-year-old fiancée Claire Howarth, also an officer, and then staging a car crash to make it look like an accident.
The unit prepares the case for court, interviewing witnesses, compiling CCTV and forensic evidence and carrying out house-to-house enquiries, leaving the "real" detectives to concentrate on the more difficult category A and B murders.
The figures suggest it has been a success. Since the unit began its investigations, the average time for a murder to be solved in Manchester has fallen from 65 days in 2007-08 to 33 days this year.
But not everyone is happy. The increase of civilian investigators (CIs) in police forces is a contentious issue in the eyes of some of their colleagues.
The line from the Police Federation, the body that represents England and Wales's constables, sergeants and inspectors, is that only warranted police officers should investigate crime, and that civilians are taking jobs which should be filled by "proper coppers".
But Mr Tattersall dismisses their fears. "We take the weight off the other teams of detectives," he said, "and allow them to concentrate on the more serious cases. We are not replacing anybody."
He stresses that 20 of his 23-strong squad are retired police officers. The three others, who have never held a warrant card, previously worked in the Department for Work and Pensions, police support staff and in a solicitor's office. Mr Tattersall insisted: "Our recruitment criteria is strict. We look for people who have investigative experience, whether that be in the police or another walk of life, and they need knowledge of the legal system."
He was a detective from 1974 until 2007, when he retired aged 52 having investigated more than 200 murders. "Between us our team has hundreds of years of experience," he said. "How many of the people who criticise us have solved as many murders as us?
"At the end of the day it doesn't matter to me that we are not warranted officers and it doesn't matter to the families we deal with. They just want to see justice for their loved ones."
CIs' attraction for forces is their cost-effectiveness. A CI salary is about £24,000, whereas detective constables earn up to £34,000 and detective sergeants can make £40,000. The cost of running the category C unit is 55 per cent of its detective equivalent.
The Police Federation fears that CIs will be used to solve the current shortage of detectives. As revealed in this newspaper last month, there are 5,000 vacancies in CID departments in England and Wales. Many young officers prefer to stay in uniform because of CID's unsociable hours and no overtime.
Simon Reed, the vice-chairman of the Police Federation, criticised Manchester's use of civilian investigators: "They do it because it is much cheaper than investing in CID, which is what forces need to do. Could you imagine if they did this with nurses? Imagine patients were being looked after by retired nurses and people who have never been nurses. Both are skilled jobs, but there doesn't seem to be the same value on the skills detectives have."
He added: "If you take this to its logical conclusion you could civilianise every police job that doesn't require arrest or force and all that police officers will be doing then are things like public order and firearms or kicking people's doors in. That is not the image anyone wants the police to have."
The criticism of the federation has stung members of the unit. Vincent Chadwick, Mr Tattersall's deputy, said: "The Police Federation slags us off and calls us the Dad's Army unit, but the most frustrating thing is they have never visited us, never spoken to us about what we do. I wouldn't mind so much if they came and had a look and decided we were a bad idea." The Metropolitan Police has visited, but says the model is not one it will adopt.
If Police Federation chiefs had visited they would have met Andrea Steadman, 34. She is one of the CIs with no previous police experience. Before joining the unit she worked as a solicitor's personal assistant at the Greater Manchester Probation Service.
Sitting in the incident room (the door of which bears a "Dad's Army" sign, a swipe at detractors), she said: "I was thinking about joining the force then saw an advert. I knew I would get the chance to work on investigations.
"The most memorable moments have been big cases like Mullings and my first case. It was the first time I'd seen a person that had been murdered. It is something you cannot prepare for and obviously never forget."
She added: "You might get some people walking past you in the corridor who stick their noses up or make comments behind your back, but most officers are really supportive."
Martin Rigby, a 49-year-old retired detective who served 18 years in CID, added: "You don't have to be Miss Marple to work out that one of the main reasons we're here is because we are cheaper. But everyone in our unit has the support of the rest of the force.
"They recognise that although, technically, we are civilians we are experienced investigators. It is disingenuous of the Police Federation to give the impression that we are a bunch of milkmen and window cleaners who don't know their arse form their elbow when it comes to solving murders. That's clearly not the case."